Premade teams flaming and reporting.

Due to a recent chat ban on my account, I'd like to ask about how riot can justify banning people automatically based on chat logs. The basis of my ban was a chat log from a game where 4 premade players flamed and reported me due to their in-game mistakes. In the gameplay, I'm a gangplank mid vs katarina (a notorious roamer). On every occasion the katarina roamed I pinged that she was missing, in every instance in this case i knew exactly where she was going and pinged the exact people on the map as she was in vision. My teams scores went something like this: Mine - 1/3/2, adc - 0/7/2, support (miss fortune...) 3/5/1, jungle - 0/8/3, toplane - 4/5/0. As you can see, Mine was amongst the highest. Obviously the petty insults and comments came first from the 4 premades, "nice ss" (which i did), "at least push your lane" (which i already was) then it skipped straight to blaming me for them dying, lying about the reality of what was happening (the miss fortune claimed that i wasnt pushing lane when i was etc. The jungler then decided just to say "ok 4 x report" out of nowhere. This is the problem. 4 People reported me, I got a chat ban end of story, no checks made as to whether it was a legitimate cause.

TLDR ; 4 PREMADE PLAYERS BLAME THE MIDLANER FOR THEIR OWN MISTAKES AND REPORT THE MIDLANER. THE MIDLANER GETS BANNED.

How can riot justify these bans, or how can they suggest preventing these situations. I'm sure I'll be told you just shouldn't engage in discourse with flamers, but that seems like the victim being blamed (for lack of a better term).