Does Riot have access to post-game logs?

All the time I'm getting toxic players in my games that say hateful and rude things in post-game. Then when I say they'll be reported, I'm told "Go ahead, Riot can't see post-game anyway!" Is this true? If so I really feel like Riot should change that because there's a lot of toxicity that could easily slip by them because of that.

Note: After writing this out, it feels kind of like a dumb question, but multiple people have said this so confidently that I couldn't help but ask.