It might be possible but I hope they won't cause it affects their reputation.
Believe or not, Coinbase has a huge number of account holders last 2017 and even other exchangers are the same cause of bounty are really great and more traders come to sell their tokens/coins. But that was a short stay cause when the bull runs stop, they will no longer use it again. They have a lot of registered users but couldn't think how many are still active by now.