Plain and simply the report tool is just an automated system where a certain number of people report after game it auto restricts the player. The matchmaking system is still broken in lower elo yet riot refuses to acknowledge it so let me break down in understandable math why it's a useless "feel good" button after games instead of imposing actual punishments to keep players happy without addressing the major issue.
Say there are 250,000 games played in a single day between all elos from iron to challenger. 5 players per game. That equates out without accounting for a side variable to 50,000 unique game
Now let's say 60% of those games have a hard feeder or someone who's macro play clearly shows they shouldn't be in that game (I've also been in a game I should have never been in). This comes to 30,000 unique players/games.
Let's go with 30 minutes per game on average with current meta. This comes to 900,000 minutes or 15,000 hours of gameplay per day of games where someone has reported someone.
Say riot doesn't pay employees a salary base and are factored under hourly as I'd assume. Say the average employee just works the standard 40 hours per week.
Riot would have to employ 375 people (weekly basis) who strictly monitor reports on straight 8's with no breaks/lunches.
This is a California based company so wages I'm going to put around $15/h to undercut numbers just for perspective base.
This would come to $225,000 a week ($11,700,000 a year) they would spend on employees just monitoring player behavior/reports. No good business model would ever do such a thing. If you look at their last fiscal quarter and subtract this numbers from it you'll see that this in turn proves riot in no way shape or form follows up on reports from people who are genuinely pissed and is the solid #1 reason why league has such a toxic community. I won't post the last fiscal quarter numbers but rather if you're curious look them up. They are public information.