Because a user could clear their inventory with similar speed by dumping items into a regular tab
Unfortunately this is not the case. I didn't run any tests but I would guess it takes about 5x as long to ctrl click into a dump tab, then re-sort later, than it does to ctrl click into autosorting tabs. I've spent enough time trying to optimize the chaos recipe that I can say, autosort is an enormous timesave.
The difference is to stash organization what loot filters are to loot organization. Loot filters are free, so I expect this feature to be free as well.
They're free QOL features, yes.