Why is qualifying for the association bonus (at 200 reputation) not mentioned in the privileges list in the Help Center?
It's not the purpose of the Help Center to list all privileges. One could even question if this is a privilege at all, since all you get is more reputation. In any case, many more privileges are missing, e.g.
- With 150 reputation you can vote in an election
- With 2000 reputation you don't get a popup asking to comment when downvoting a post
For a complete list of privileges and corresponding levels, see the FAQ Reputation requirements compared.