If anyone on here is willing to team up with me (outside of comp perhaps so I don't trash anyone else's score!) then I'm Midweek#2599. Probably be on a fair bit this weekend.
Might be luck of the draw - overall pleasantness of teammates can vary a lot with time of day, day of the week, etc. My experience of playing at 'schools let out time' is generally worse (good technical players, poor teamwork, lots of pointless smack-talk and aggression) compared to later in the evening.
Generally speaking "play something else"
should ideally mean "snipers are weak on offense" or "we already have too many tanks" or similar. Unfortunately, in real life it often means "I want to play my favourite DPS character, go personal healer for me" or "I read online that the pro meta is the following six choices for every map, so anyone picking anything else must be rubbish". I'd take it with a pinch of salt.
If people were calling you rubbish (and assuming it's not because they are just idiots... which is probably the more likely option) it may be because either you were playing a typical 'tank' character but not not protecting them, or they were telling you to swap for a specific reason but not letting you know. Examples of that are if the enemy have a Pharah your teammates might tell you to swap to McCree or Soldier 76, the idea being that they have the best setup for picking her out of the air; or saying swap away from junkrat if the enemy have a Zarya as her self-shield powers her up when it blocks damage, so junkrat's spammy-grenade playstyle can basically make her very strong. Too often they will assume you know this and just say "X, switch" or "X, go soldier", without explaining why. You also get a lot of people who just say "cancer team" or "FFS, all X's fault" at the end without having said anything the whole match, which is anything but constructive. It even happens with really close, fun games that come down to the last second of overtime. Some people just can't take losing.
My ID's on the master list (check back a few pages for the link) - friend me up. Happy to team up for comp or QP - rank isn't that big a deal for me (I'm not chasing the points).