No, it’s the fault of whoever is perpetrating toxicity.
If your neighbor sets your house on fire, do you go set his on fire? No, you call the police and the fire, and they come fight the fire/arrest the neighbor. Likewise, you mute/report, and Riot will deal with the trolls. But once you set his house on fire, the police, when they come, will deal with both of you.
In your example: Riot puts tape over the hole they can see - it’s much easier to detect/punish toxic chat. While they do that, they’re looking for the holes they can’t see - and patching them. They’re patching every hole though - not just the ones they can’t see.