I think the "privacy" of players policy and the occasional IFS notifications received are to make us believe the system is working when its clearly not.
Why would Riot admit that right now their report/reform system doesn't work? They wouldn't. It would make more people quit because then it wouldn't just be a "rumor" or "feeling" that they have little power curbing trolls and non-reformed players.
Ultimately, you are free to believe what you want to believe in.
So do as you wish and not believe what Riot says about privacy. Though someone who is more versed in privacy laws would probably tell you what are the rules Riot needs to follow.
Keep in mind that different countries have different laws, if LoL wants to be played in those countries, then the game operators (ex. Riot, Tencent, Garena) needs abide to all of them. So it wpuld make sense to follow the strictest rules so they'd be able to have all their bases covered at all times.
Ya know, it would be a lot easier to keep toxic players out of the game if all accounts were required to have multi-factor authentication like SMS verification. They could then blacklist all contact information associated with the profile. Changing an email is easy. Changing a phone number? Not so much.
EDIT: Yes, I know that phone numbers can be spoofed as well, but even most tech savvy individuals won’t go through it if they think it’s too much trouble.
