In pubs, players learn the ancient art of disconnecting when downed since they realized they can get back into the action sooner instead of screaming, "LiFeLiNe ReZ mE!!"
Then in ranked, a lot of players are still in that pubs mindset, so they would often leave too. However, a lot would wait to time out before they leave. These players either don't care, or don't know banner crafting is a thing, (which if its the ladder, it means that they do not care to learn how the game is played or about its changes, so they're better off not being on the team anyways).
Other reasons why they'll leave in ranked is that the "hidden MMR" is awful. You get put against players way above your skill, and your teammates are almost always way below your skill, and you're expected to just clutch as a solo. Players who leave in these instances are used to useless teammates and rather take a loss instead of spectating the "noob" or "bot" teammate running around aimlessly.
TLDR;
Pubs
- Disconnecting gets them into the next game sooner
Ranked:
- Pubs disconnecting mentality
- Matchmaking is broken, (going against players who are higher skilled in unfair matches with lower skilled teammates)
- Teammates are a joke, (noobs or bots)
Oh, and lets not forget that if the server crashes, gets DDOS'ed, or otherwise stops the match, you'll get a penalty for "abandonment", when it wasn't even your fault in any shape way or form, and EA/Respawn hasn't done anything about that kind of loss, so its clear that if you lose points due to the game or server's own errors, too bad.
Also don't bother to play with friends. I've already tried a duo and trio party, and all that does is made us go against the top preds and all the cheaters playing. The more you pre-stack, the more the game thinks you can 1v3 the top players and cheaters. This is especially when both teammates are new to the game or don't no-life it as much as you do, (yup, it doesn't care about their skills, if you're in their party. They'll get sentenced to your level of matchmaking flaming inferno, and the heat is cranked up to the max since your there).
I'm at the point where all the friends I enjoyed playing Apex with had stopped playing and went on to The Finals, Fortnite, etc. and every match, no matter the mode, my teammates are usually unable to hit things, and pretty much all the enemy players are diamonds and up (25%), smurfs (5%), or cheaters (70%).