Honestly if someone is literally asking to get put on a list of toxic users I see no reason they shouldn't be accomodated, it will be doing a favor to those of us who appreciate having the feature.
They posted an explanation in the tesseract community, but it boils down to they want the fediverse to succeed and replace reddit, but there is a contingent of toxic users that they feel is hindering that goal so they precompiled a list for new instance admins.
It's fully optional and can easily be disabled in the UI
why can't you just let people use their own computers how they choose