The shitty thing about reports is that they're sent to me, not directly to itch.io staff. Even when I report the reported content, it goes straight to me haha
Itch.io staff does seem to become aware of accounts with enough reports though, so it's a team effort. Sometimes accounts do get globally banned before I have the opportunity to ban them here. If I were to guess, one person reporting all of their comments does more than mass reporting one comment.