Why couldn’t they? Console games have had mandatory patches for years and years.

Just because it’s on the disc doesn’t mean the binary has to load it.

I was thinking of the PS2, but you're right, modern consoles have patches.

As for mandatory patches: you would at least have the option to play single-player offline without updating.

That is a good point. Short of buying and holding the physical media Steam is the best thing for gamers IMO. Even physical media have problems. Eventually it won't run or work on Windows, yet steam games will often get updates to work and get bug fixes. AAA titles work a little differently these days and tend to be massive and are honestly not even done when released these days.

Good Old Games is the best thing for gamers. The only thing that Steam does better is the size of the catalog.