You are mixing having your own physical copy with needing to run games straight from the disk. Nevermind that there's no reason that games couldn't be sold on faster cartridges, you can still have a physical media that can install a game into the console. Offline, without relying on an online service that will inevitably close eventually.

As it is, with disks and cartridges, they can't make it so absolutely every game must check with their online services. They have to make sure grandma in the boonies can make little Timmy's game work right out of the box. Without them, there's nothing stopping them. They could even straight up say that "no game could be expected to last more than 10 years", and I see enough people that already seem ready to fall for that. Nevermind that to this day there's people playing the nearly 40 year old Super Mario Bros.