In theory, why would you want 5 different setup pages for 1 setup, just to change some optional things?
Why would you want rules in signup + rules in setup, just so players have to walk back and forth to see what was originally and what was changed? This goes for everything. It's unnecessary mess, it's ugly. One setup has "host reserves x color" another has "host reserves y color", when neither has any point in being there and that's the sort of thing that would be dependant on host rather setup.
Why wouldn't you have
more variety freely available instead of having force it if wanted after, technically, the setups were already approved?
Freely available variety for the cost of not having optional thing pre-determined. Things that should have no place in setup pages to begin with.
Anyways. Doesn't matter. But it's ugly and restricting and wrong.