Does reporting people for leaving matches early actually do anything?

This take is all what is wrong with Apex especially the last part about ranked - it is still played 9 out of 10 games as pubs by people who are below D4 because rank system allows to rank up vs e.g. Valorant where people like that would be stuck at best in Silver aka rank hell and would be actively punished for every stupid game they play not as a team while being encourages to join a team (Premier e.g.) and get better.

And then after D4 people just turn to 3stacking (rarely, now going away for 2 weeks) and cheating (more so than anything else) because latter is 100% compatible with that trash soloq / lone star mentality.

People in Apex are soft and not smart (mildly put) and unfortunately they need more playgrounds aka casual modes where they can do whatever they want. Pity such a game as Apex that has imo huge potential for competitive scene is stuck with 20 teams over 7 years and noone really care anymore as it sounds about them either. And even further from the truth is competitive spirit. You either "have fun" playing like a kid with no penalties or cheat your way to whatever rank and repeat season after season just with different skins for as a reward.

Like I honestly would ask those cheaters and casuals - why you even play ranked and flex your whatever Masters rank? You don't compete, noone knows you, you are "above average" player just as any "hardstuck diamond" who don't care even when you carry them for the most part or show you badges / skins... why bother cheating if you don't have aspiration to become better and got competitive / pro? I don't get it.

Back in my days when I started people actually used e.g. wallhacks to understand which places of the maps are more popular, what angles people hold, how to prefire based on sound ... yeah they cheated (much less frequently than in Apex where every game in Diamond is featuring at least 1 cheater) but they had higher goals.

To sum it up: most clients of Apex are casuals that don't like to be on a losing streaks, punished, challenged skill wise and so changes that  would do that will probably never happen.
I am actually surprised how drop zones survived given negative feedback from casuals, I was certain they will not hold to  D4 lobbies for more than a split. Kudos for still keeping them. 

"I'll be having a great game and getting close to a 20 bomb and they'll just leave."

Take the combat blinders off for a minute. Ask yourself what experience the quitter was having before he quit. Odds are high that he wasn't having a great game and wasn't close to a 20 bomb. Odds are he'd either never been in the mode before and discovered (surprise!) that it's horrible and he hates it, or that he's fed up with cheaters, or that sbmm pulled a "respawn" where his teammate (you) are in it with good performance and stats while he himself is hopelessly outclassed and being downed every five seconds before he can even aim his weapon. People don't quit matches to frustrate their teammates. They quit because they're frustrated. Sure, it's nice if people learn how to manage their frustration in productive ways, but we're talking about a casual mode in a free game that's populated in large part with children. It's not a high bar, and a quit penalty won't raise it.

Blame short attention spans. Blame horrendous matchmaking. Blame bad parenting and socializing. Blame whatever you want. But remember that if you expect to solo queue AND get teammates who won't quit then you need to stick to ranked.

Known issue for eternity, I remember a while ago there was a huge discussion here in forums about applying same mechanics to pubs as in ranked = can't leave for like <5 min after death, but based on that discussion alone it was clear that majority of people are just ... interesting :D to put it mildly and actually are all for situations where 10+ teams out of 20 drop Fragment or Quantum or whatever other spot and repeat that 100 times per day.

That's just how "good" Apex community is :) and a clear sign how streamers who do that and in some cases succeed killing multiple people / teams have influence these highly susceptible people :)

That's why I pretty much never play other modes and treat pubs as a firing range with better bots to keep my brain up to game speed / test some legends / weapons combos I find interesting and potential for ranked. Otherwise I just go straight to ranked always.

Same applies to outcry of most casuals about what is in my opinion one of the best / only improvement over past years = drop zones. I it sad to see when matchmaking at the end of splits match me D4-D1 player with some Plat2/3 who are almost seeing drop zones for the first time and can't understand how to play them, get frustrated from the start of the game that they as Plats now need to play this drop zone mode :P

It's just Apex...people like to aimlessly drop, hold 2 buttons and then re-queue and/or rage on teammates for their mistakes. Just yesterday I had a player who died 3 times in all 3 fights we took by running into 3 people I pinged and asked not to (dude was playing Wattson :D) -> while dead he was trash-talking in chat including complaining about me looting (I was Loba, was looting and dropping bags, batteries and other good stuff for my teammates who kept dying) -> Wattson didn't use any fences all game -> eventually in zone 4 they decided to split up, aggro two different teams who basically sandwiched us and killed. Wattson kept talking about me looting and having no impact = I ended up doing 650+ damage and have 1+2, while they both did 1 kill and 300 damage and died 3 and 2 times accordingly. Current P2 level players aka past Diamonds :)
To sum up: people even in high ranks do this stuff...and they still think they are doing the right thing despite failing for 1000000000 times. You just can't change that.

I think the best thing players that do this is to make sure they receive nothing:

Kills and Damage: You keep all kills and damage earned prior to quitting. (Pubs)

It baffles me why - especially when it's the Jumpmaster (which it mostly seems to be) - hot drops the team, gets knocked immediately, then leaves.

Honestly I doubt reporting anyone does anything at this point 

I get more tilted in WC, I'll be having a great game and getting close to a 20 bomb and they'll just leave. Then since they're gone the 2 of us left have to be super conservative since we've lost our 3rd life

It happens a lot for me too. But I don’t tilt as much in WC considering I get to come back. It really bothers me in ranked, but i genuinely just think because they go down then you will too. 

its an ego thing. They don’t have faith in your skill cause theirs let them down.