Based on their extensive internal data and surveys, Riot believes that negative chat hurts their bottom line.
If you're old enough, you may remember old geek stores or conventions (wargaming, computers, anime, D&D, board games, whatever) didn't have personal hygiene rules. Geeks focused on their passion, and not societal niceties like bathing. Everyone had to get (thicker skin) used to it if they wanted to participate. But, spending hours in cramped locations with them isn't really very pleasant. Many people who tried to enter, just left to not return. That's a loss to the business owner. Others just spent less time browsing, and directly because of that purchased less. Another loss.
To increase the market for geek products and services, some stores started posting and enforcing hygiene rules.
Analogously to chat restrictions, there were 'community deodorant bars'. If you stank enough for an employee to notice or a customer to complain, you were given the choice of using the community deodorant or leaving. It really helped. It was incredibly embarrassing to be forced to do that.
Now, most places no longer post hygiene rules. It's just an expected part of participating in normal society.
If you're young, you're most likely here, playing a computer game, BECAUSE of the hygiene rules that were put in place back then. It massively changed the scope of who was willing to participate.
The rules on chat are just another form of hygiene.
People play fewer games per gaming session when they encounter negativity.
People take longer breaks between gaming sessions when they encounter negativity.
People decide to no longer play.
Can you imagine standing at the counter, looking at the community deodorant, knowing that your actions have been proven to drive away customers?
If you want to continue to stink, there are other games that don't have hygiene rules. You can go play those games.
