The rules become flexible and abnormal for the sole purpose of supporting someone's agenda. Maybe enjoyable or appreciable in a meta sense, but from a game mechanic PoV it makes strategies meaningless.
Part of the point of variant sudoku is discovering / inventing brand new interactions you've never seen before. And crowd-sourcing votes on whether that discovery process is fun. You are basically getting introduced to a new set of axioms and have to discover and prove theorems.