I don’t think you understand. If a person has a one-park ticket and Mummy is closed, that’s it. If ET closes, there’s no other all-ages practical ride in Studios. If MIB closes, there’s no other mid-thrill family ride (that isn’t F&F).
Universal has only started leveling out with one-day, two-park tickets in the last few years. There’s still a large percentage of daily guests that only buy a one-park. For them, it doesn’t matter what’s in the other park. Because of that Universal looks at refurbishments based on parks, and not the resort.
Conversely, Disney has effectively gotten a point where the majority of daily guests are on park-hoppers.