Definitely valid points. I've complained many times about the people who just post and bail , even when there are thoughtful responses...
That said, it would all be based on the type of npub. Like, I follow some npubs that are like apps, podcasts, or other content like news etc. In those cases, I wouldn't want to discriminate against ratios because I don't expect interaction back.
I guess it becomes a UX problem at that point, and would depend how the client categorises different types of npubs/shows the appropriate metrics so people can determine quality follows based on the content type.