I think the value of being able to choose the best N of M is much better than the value of seeing progressive post quality increases, especially considering that most high-quality posters will inevitably end up applying here when the slots open.

The top quality posters inevitably join such highly competive contest in the top (highest) campaign. In my opinion, there are at least three causal components that motivate users to do their good quality posts and improve posting quality over time:
(1) Their internal purpose to improve themselves by learning more about bitcoin, blockchain, and cryptocurrencies.
(2) The merit system, that requires them to do quality posts to rank up.
(3) The top campaigns that require them to compete each other (among top quality posters) to be accepted by managers.
Personally, I will keep applying here whenever new open slots announced by manager.