For example, if one category is "no esc" where you aren't allowed to hit the Esc button, then a variable/filter for a glitch that requires hitting Esc isn't a necessary variable on that category. As it is right now, you can only set a variable for all categories or only one, but you can't set it to "all except one" (or "all except these few") unless you list the same variable x amount of times and set them all to each different individual category, which just becomes a mess in the game settings page if you're listing the same variable over and over.

It's a technical limitation and an interface problem. Adding an option for 'all categories excluding x' would bloat the settings when the same thing can be accomplished with duplicate entries for the other categories. I agree it's kind of annoying but not really a problem. They could implement a checklist system for which categories a variable applies to.

A workaround if you don't like duplicate entries is to mark it as not required. That way people submitting a run for the category without "No Esc" can leave it blank. This would allow it to be blank for the other categories, though. You'd have to pay attention to that when approving runs.