It doesn't matter if you get reported for picking Nidalee support. You don't get banned for picking off meta things (unless you're also trolling while you do it). Riot has stated time and time again that they will NOT ban you for picking something that isn't in the perfect "meta."
If you got banned it wasn't because of your pick, it was because of how you interacted with other players during the game. If someone says "wtf a nid support gg" and you say "It's cool I main nid support I'm not trolling" then fine. If you respond instead with "Fuck you I pick what I want you suck just let me play" then you're getting banned. Unless you have actual proof that you're being unfairly banned (which you don't) then you can't possibly continue making the claims that you are. It's not rare for someone who got banned to conveniently forget all their prior transgressions and just assume the ban was from the last game where they were "barely" mean or after weeks of harassing and intentionally feeding they played a normal game but played something like Nid support and got reported, then saw a ban come through after to assume the ban was for the support pick and not the stuff weeks before.
Additionally, it's not like you have brought any crazy insight into new things Riot should implement. If you have spent any time in this subreddit at all you'd know that all those things have been posted time and time again in Rito Plz threads, and every time there are posts discussing why it wouldn't work or could be abused.
Additionally you keep comparing DOTA and LoL and that's kind of unfair. Sure they're similar games, but the scale is completely different. I don't even know the actual current numbers (feel free to look them up if you think I'm wrong), but last time I checked DOTA had like 8 million active monthly players while LOL had about 70 million. OF COURSE you're going to run into more trolls in LOL. It's a vastly larger game, and being the more "mainstream" game it also attracts a lot more casual players, and a lot younger players as well. The system is working pretty well for how much it has to handle. Instead of worrying about all the other toxic players, focus on the fact that you should stop being a toxic player yourself.