Because a lot of Switch games require downloading the finished game to be playable. See which here: https://www.doesitplay.org/switchCartsRevisions
And from my experience, I can just refuse the update every time. Heck, from a speedrunning perspective it's probably better not to update them, since the updates patch out a bunch of tech that makes them more fun to mess around with (easy item dupes in Tears of the Kingdom, easy out of bounds in Mario Wonder).
Any number is too many, I agree.
My switch is (and will remain) offline. I wasn't aware some games may not play - even some first-party games like super mario 3d allstars needs updating, according to this.