It is absolutely harmful for the user experience because it's tied to a boost in the visibility of your tweets. It's essentially made replies a useless avenue for interesting content.
Instead of the top replies to popular posts being tweets that have been boosted by a signal that arguably indicates quality (views, likes, retweets, replies of their own) tweets are boosted by a signal of the opposite - the poster's willingness to pay for visibility of content that couldn't rise to the top on its own merits or that of its poster.
Replies to popular content are now a wasteland for interesting content or discussion unless you've mass-blocked Twitter Blue subscribers - definitely harmful.
Instead of the top replies to popular posts being tweets that have been boosted by a signal that arguably indicates quality (views, likes, retweets, replies of their own) tweets are boosted by a signal of the opposite - the poster's willingness to pay for visibility of content that couldn't rise to the top on its own merits or that of its poster.
Replies to popular content are now a wasteland for interesting content or discussion unless you've mass-blocked Twitter Blue subscribers - definitely harmful.