Why not help?
Because in this case you're just wasting your time.
If Riot ever decides to do anything about botted accounts, they're going to do it, and they have the information they need to hit them all. Do you really think they're going to go through some list a player made to get the same information that they already have? Even if they did not track player activity internally, they would need to go through every single one and investigate them on a personal basis... it's not like they're going to ban accounts based on your word alone. That's not how these things work.
More than likely, almost every botted account currently operating is going to get away clean, and they'll put measures in place to prevent future botting while possibly banning some bought accounts to set an example (that will probably be ignored but whatever).
If community involvement would actually help with this situation, they would have asked for it.