The thing is, those mass reports don't actually mean anything. The people who complain about being banned because they got mass reported usually don't understand how the Instant Feedback System works. It only takes one report for a match to be reviewed. And having nine reports in a match doesn't make the review any more urgent or important than having one report. 1 report = 9 reports. So, if nine people in a match gang up and report the last guy, it will review the match. But here's the thing. If the guy didn't do what they reported him for... all the reports are thrown out as false reports. Doesn't matter if there is one report, or nine. If they are false, they are ignored.
If someone is ever punished without actual toxicity in their logs, they can always submit a ticket to Player Support, and if the punishment was issued in error, it will be removed.
But the easiest way to avoid this potential problem is to simply not make comments about the mistakes of your teammates. Or, if you feel like you have to point out someone's mistakes to help them learn from them, do so in a constructive manner. For example, instead of saying "my support dives a vayne with sustain support and full minion wave and died" you can try saying "might want to watch trying to dive against that sustain support with so many minions. she's got crazy heals and their damage adds up fast." It says the same basic thing: i.e. your support screwed up, but it isn't talking about them in chat like they aren't even there, it's not insulting their intelligence, and it might just be something that they needed a little reminder on.
