Quite frankly, the OP's original came is completely unreliable, anecdotal at best. If a real "survey" was done, this post would be something like:
We surveyed 315 number of people at the 2019 Twitchcon and asked the following questions:
- Have you ever had an account permanently banned on League of Legends?
- dot dot dot
- Etc...
Of the 315 number of people surveyed, 24 confirmed they had at least one permanently banned account and 3 declined to answer.
Instead we get the wishy washy "of the couple hundred people I've met 20-30..." which basically amounts to hogwash.
If the OP had actually conducted a real survey, we could at least talk about methods, quality of questions, method of attracting survey takers, etc. As it is, I'm not even convinced any sort of survey was was ever performed.
Also, just to toss in my own anecdotal evidence, in 10 years of playing this game no one on my friends list has ever been permanently banned.