My first thought was “Yes, that’d work fine.” And it would solve the problem of needing back up to the top of the list to “Select All”. But I tagged another category just now and noticed the wrench icon I need to press to do anything with that list is all the way at the top of the page. So I still would need to scroll all the way down and back to the top whether all the topics get selected on the way down or not.
Maybe make the wrench sticky in addition to auto selecting as I scroll?
The other issue is an expectations problem. When I selected all the first couple of categories I did, I assumed it would select all topics in the category. I thought it was strange that all these categories had exactly 30 topics. But then I went back to see if I’d tagged everything the way I wanted and noticed that they have more than 30. It’s just the first 30 that happened to be loaded in that I selected.
I can certainly understand it’s not a good idea to load in thousands of topics if you happen to press one button. But it sorta feels like a broken promise when it turns out “all” just means “all on the page”. I don’t have a good suggestion other than maybe warn folks when they do a bulk action that they should check to make sure they got everything they want.