I've been playing since about a month after release and have since reached lvl 81 (just to show I put in quite a lot of game time since I started).
In my first month of play I came across ONE single griefer who TK'd people on purpose. Considering I'd played hundreds of games I thought this game was a shining example of a great community.
However.
The last three(ish) weeks or so, I feel like I'm playing a whole different game. About 1/3rd to a quarter of my games involve randoms with really toxic behaviour. Training mobs on you, throwing barrages on the group for fun, destroying our own sentries in defense missions...
But there's one thing that is apparently suddenly a "fad", I guess? That is kicking someone from the game right before extraction. Seriously, I've run several full 40 minute rounds, usually on decently high difficulties (7-8), with no real communication with any players whatsoever, let alone tk's or toxic shit, and then you suddenly get kicked as soon as the Pelican is on the ground.
WTF gives? I don't know if it's a reportable thing, I doubt it, but I sincerely hope it's just players getting somewhat bored while waiting for more content and that it'll pass, because if this is going to be my regular experience from here on out, I'm going to look for something else to play. Not the devs' fault in any way.
I like the final fantasy 14 method where in a four-player dungeon, you have to vote kick, it's not controlled only by the host.
Which then gets hijacked completely once two assholes join in to ruin your game.