The difference is the price of buying discs vs. buying from a digital store that has no competitors.
I’ve bought almost exclusively second-hand discs for my PS5, because they’re like half the price for the exact same content.
Sadly it’ll probably be just a matter of time before those will be phased out as well, one way or another.
They can, difference is a vast majority of people don’t want to buy/build a PC, or deal with a PC setup in general, they just want to press one button to make it work and sit on the couch. So the easy option for them is buying a console, it’s plug and play, while a PC requires quite some setup.
So we need Steam Box. Steam Deck just works 99% of the time. I can only complain about the desktop mode being buggy and non-steam games being a pain in the ass to install.