No, Aarakocra are not universally banned as playable characters. However, many DMs are aggravated by the inclusion of flying races. Flying characters take more work to manage. They often have a different dynamic within the campaign that might make things more challenging for the DM. The DM is not required to acquiesce to everything a player wants. However, player enjoyment is one of the most critical parts of DnD. There are many ways to mitigate and work with a player who wants to play an Aarakocra. Players also need to recognize how much work DMs put into their campaigns. It is a labor of love for both the players and the DM. It's most important to have fun.