There should be definitely something like this in the game, because without it, some games become even more frustrating than this awesome matchmaking system can create.

For example:
Players Aldzor and TheUndertaking were in my team, where we (lvl 14-17 as most of the team claimed) ended up against pay2win 20s, that is not so uncommon in this game, but still we managed to move at least to the 3rd point.
BUT they just stopped playing, because they realized, they cannot win (no wonder when we were so outgeared by enemy team). But instead of that, they should have left and maybe, just maybe that broken system could supplement them with some good players and we could have still won that game (wouldnt be the first time for me).
And since there is no working report/kick system in this game, this happens pretty often and the game gets frustrating, because of some douches you dont really have much choice then and only leave and lose exp, or wait and suffer for 15mins.

AFAIK the vote-kick system is in development.
And inactive players are kicked out after minute or so. They can hang in by doing something, but if they are just standing on respawn point they will be kicked out automatically.

yeah, moving once in a while is the way...

Nah chatting with you.
Anw, you can't afk, because you need to do at least 50 pts to gain xp.

yeah, I feel you there.

Having a system with kicking/banning inactive or griefing players would be amazing

There was a game in Alchemist castle where we were attaking, and one of our own were lowering last 4th platform into the acid with +4 of our team mates in the pit ...
Ohh.. and to mention he repeated that 3 times!