PrincessEli

For one, things like cloud storage are obviously not particularly viable to have the customer host themselves, on premise.

Secondly, some things can be extremely intensive to process, and thus performed on specialized, high end hardware rather than over hours on whatever shit phone the customer is using

For one, lots of software just flat out isn't open source. And plenty of it is far from short lived

You're... Confused why software can require server side features?

You clearly haven't dealt with the "average user". Get ready for a boatload of idiots who followed some crappy tutorial for "how to get it for free" making a problem for support or review bombing the app when they lose all their data through incompetence.