It's not propaganda, it's just basic computer science.
Literally how is a disc needing to remain inserted to validate the copy running from the SSD as a technical necessity for the required bitrates of modern games, when it's all still done locally, in any way practically different for the end user's experience than running it directly off the disc where the disc needs to be inserted the whole time anyway, and comparable to a game key card that contains no game at all and only lets you download a digital copy from a remote server? You're quibbling over semantics and making it seem like something it just isn't.
1) PS5 discs have the games on them locally. You have access to the base game in full, minus any patches or content not on the disc, obviously, for a fresh install any time if you delete the game from your SSD to make room. You'll never need to connect to the internet or depend on a download from a server to access the content of that disc.
2) Optical storage isn't fast enough to stream assets properly anymore. The disc needing to stay in the console is copy protection since you've duplicated the data and they want to make sure it can't run independent of the paid copy on the disc. That's it.
3) Key cards don't contain the game, they contain a voucher for a download that needs to be pulled from a server, otherwise they're useless.
4) Since one contains the full base game accessible locally regardless of technical limitations requiring the data to be moved to faster storage before use, while the other contains no game data and requires you to retrieve it from an external source you might not be able to access, they aren't comparable, and it's disingenuous at best to equate them on a superficial similarity of not playing the game directly from the physical storage medium you bought to access the game.
PS5 discs are objectively still true physical media. There's just an extra *fully local* step to access the data properly because it's literally just too much data for an optical drive to stream directly anymore. It just doesn't work as a matter of the technology.
The level of propaganda Sony has gotten away with to convince people their discs are still true physical media needs to be studied.
The last console that could fully store and read games directly from discs was the Wii U.
This whole war against GKC is performative as hell.