In my experience in ranked there are actually a few factors that determine result at the end:
1. Soloq (getting random teammates 99% totally not interested in teamworking and/or communication but easier lobbies) vs 3stack (teammates that will communicate, have similar goals, but will have harder lobbies).
Sidenote - based on exprience 2stacking is the worst as you get 1 random yet if not the same then equally harder lobbies as with 3stacking, so that is the worst imo.
2. Caution (soloqing - knowing that mistakes will be made, teammates will not have your back) vs Ego plays (3stacking and thinking that now you will face all those soloq nubs and pick them off one by one easily)
3. Teamwork and playing off eachother - in many cases even biggest criers about how bad are soloq teammates will play ego game (my kills, my damage, my loot, everyone attacks) vs playing their roles e.g. support legends providing mostly cover fire while being ready to heal / pick up Assault/Skirmisher legends, recons looking around for highlighted enemies, scanning, falling maybe a bit behind or vice versa go ahead with scans etc.
In the end what is my experience and what I see a lot in Apex Legends Discord group in terms of soloq vs premade 3stack:
- number of complaints about teammates being bad is I would say equally high
- net RP gain is variable.
lower level ranks you actually can soloq through faster e.g. me as D4+ used to play Gold lobbies = took me really just <4h to get out of G2 or so to P4
higher level lobbies you will just be rolled over without a good team, maybe you will get like 4 kill game here and there but more often it will be <2 and placement wise more often than not 10th or lower because teams will hold positions, rotations, chokes and even missing 1 person on team will be crucial disadvantage
- most people actually can to a certain extent shoot, massive boost is provided by AA (average AA guy will easily give you 2+ kills per game vs average mnk probably <1), yet absolute majority do not follow the game, can't read rotations, do not know end zones, favorable positions etc.
What I am trying to say is that personally for me as D4 (now with new easy mode ranked D2/D1+) level player even Platinum players are kind easy prey, Gold and below are basically bots most of the time and I can deal with being Plat and getting Gold (haven't had Silver teammates for quite a while) and still gaining RP I just adjust my gameplay, I know what I will get (not) from Gold or below.
The bigger issue is with higher ranked lobbies where even today I got matched with D2/D1 players and I kid you not while being P1/D4 I did better than all of them in 90%+ games, in other ones they might get better stats but I was the one giving placement. => in current state Diamond and even low Masters contain total fools who can shoot (mostly play controller + Devotion + push in enemy's face + make you rat the game out after then got the kill and got destroyed by other players in the process) and nothing more. Unfortunately that leads to typical Diamond experience = getting rolled over time and time again even when sweating a lot :)
Side note: needless to say that getting P1 or lower teammates while being D3+ soloqer is absolute worst, I honestly do sometimes drop off the map and d/c when I see that teammates are total clowns and there is no point wasting time as after first minute they are all running different directions, in many cases even land in different map places from the get go (in such cases I do instadie and move on).