As others have said, the worst that can happen from mass flagging of your post is the post being hidden and Blizzard reviewing it. Nothing else will happen unless Blizzard determines your post was against the ToS.
There’s also an important thing to note here: Other people being mean to you or even breaking the ToS is not a valid excuse for breaking the ToS yourself. It doesn’t matter if you want to claim people are disagreeing with you in hateful ways, that doesn’t give you a free pass to be hateful yourself.
That said if it’s happening a lot you may want to step back and consider if you’re not doing something. I get into my share of arguments around here and I don’t get mass reported.
At least in GD, it’s not a case of “I posted an opinion people don’t like so they mass reported me for it out of spite”.