I used to use xvm myself to view stats of enemy teams and for that reason it is a useful tool. But more and more i see people giving up at the very beginning of battles due to a) their teams stats being below average. And b) they have a low percentage chance to win.
It's too often where I enter a game and right off the bat, people either suicide or say mean things in chat about the team being garbage and is going to lose not 1 minute into the game. Then they wonder why they lose so much?
If you're gonna be calling your whole team shit, they won't magically get better but you're certainly not being motivational to help them do any better either. XVM makes it even easier for these team haters to just sabotage the game right from the start, just because some computer generated chances made them think the match is already over.
I am not saying all xvm users are like this obviously, I have friends who use it and turn off the in game battle % of winning. I just think that it can be a negative impact in some games.