For example, if a creator were to use hateful language or other misconduct during a stream, but did not do so in-game over chat or voice communication, a penalty can still be issued.
Article and Riot's official documents refer to penalising toxic (flaming teammates/other people) behaviour during content creation with Riot' IPs. A negative review isn't toxic inherently
They have full legal rights to ban you for farting when the minute hand and hour hand aligned. This changes nothing in terms of what they "can" do. It's rather their public announcement about what they "will" do. If they really wanted to ban you for silly reasons, they don't even need these silly reasons, they can just ban you and are fully within their legal rights to do so.
Negative reviews are the least likely scenario for banning someone in game, as the person has already reviewed it and needs no further acesss on that account for their stream.
More likely they will punish people with an ever increasing range of 'inappropriate' that seems somewhat reasonable at first (hate speech) and end up with some minority group (LGBTQ+) being silenced through a chilling effect.
Beatings won't improve systemic problems with your genre.
There's a reason every MOBA is this toxic, and only MOBAs are this toxic. Every system is perfectly designed to produce its observed outcomes. You designed this problem.
It's a zero-sum team project. Half the people playing will lose, and none of them will feel responsible. Even though they need to work together the entire time, to such a degree that any single person can ruin it for everybody... and one player quitting counts as ruining it for everybody. You're handcuffed to these people for an hour. If this was all silly fun-times then you'd laugh it off, but of course, no, it's a competitive sweatbox.
This is a formula for a stranger in Nebraska to blow out your headphones screaming obscenities because you clicked NPCs wrong twenty minutes ago.
Compare other hyper-competitive team games like Counter-Strike. One player can clutch a 1v5. Quitting is heavily discouraged, but is roughly balanced through numeric adjustments. And most importantly, games are quick. A round can happen in under a minute. Whole matches can be as long as a MOBA round, but being broken up into multiple phases - each one a separate win or loss - lets people feel that they did okay. Even if they stood no chance. Nobody invents a racial slur, mid-aneurysm, when they lose an aim-duel in silver.
One of the ex-devs for LoL or DotA said people should get kicked just for picking the wrong guy. If you can commit a bannable offense on the character select screen, maybe the game has intrinsic problems.
To add to other commenters - its also really hard, assuming you play solo, to focus on your own performance and not blame teammates. I've never been toxic, and tried to focus on my own gameplay, but I eventually realized its almost impossible. Even though I thought that I don't care about others, and even though I managed to never be toxic, it only ocurred to me when I switched to StarCraft, where you play 1v1 and there's no-one else to blame. It was so mentally taxing, queueing for another game when you know that you just suck and will loose again to some easy build. I lasted for two months of ranked StarCraft, before I had to quit due to mental health. I just wasn't able to play anymore and was dreading the next match.
Which is something that never happened to me in MOBAs, because even though I was sure I'm only focusing on myself, it became clear that wasn't true - otherwise, I'd have quickly had the same problem as with 1v1 games. I managed to not be toxic because I hate toxicity and am non-confrotational in general, but if you are someone with less self-control, blaming your teammates just come so, so naturally. And accepting your own mistakes is way harder than I thought, which surprised me by how much.