For me it's Sony gaining full control about game prices and reselling. You can get disc versions of games for a lot less than in the playstation store.

I think there are two types of people who care. Collectors and resellers / buyers of used copies.

I play a mix of games, some digital and some physical. I don't buy used copies (I, perhaps naively, believe that I support the developers by purchasing new copies — and by "support" I mean they can make more games that I like), but I sell the games that I have finished (well, most of them). I think I buy/play more digital games than physical, part of the reason is PS Plus / PS Portal.

However, I don't like that Sony wants to abandon physical media. I believe customers should have a choice. Also, the digital versions are almost always more expensive than physical, and for years they've been misleading us into believing that digital distribution is supposed to be cheaper. Yeah, right.

If Sony controls all means of distribution, by cutting off physical media, they will further increase prices for games and subscriptions, because why not. Consumers will have no choice if they still want to play on their PlayStation.

The games in most cases haven’t been fully contained on the discs since the PS2 era.

They should be. That's why people care.

My biggest problem with this, is lack of ability to resell. I would be saying the same if they made it so the disks are license only locked to the first account that plays them.

The issue for me isn't the content of the disk, it's what the disk allows.

That being said, if I had to choose between the disks acting like a key, or the disks containing the game I would obviously choose the disk playing the game.

But if I had to choose between a disk acting as a key, or no disk at all. I'm going to choose the disk acting like a key.

Not that I've ever actually sold any of my games, or hardware. But I would still like the ability to if I wanted.

The overwhelming majority of playstation games are contained in disc and playable without internet.

We can argue about what "fully on disc" means in regards to day one patches and whatnot, but you don't need those to play the game. Buy a disc, place it into an offline ps5, install it, and play.

And you'll be able to do that in twenty or thirty years when they bring their digital purchase servers offline, too.

Because you don't own the game anymore. You're renting it from them, as long as they decide to keep it online, and they won't forever.

It's like "buying" a movie on Amazon. It's not the same as buying a bluray or DVD. It means renting it from them as long as they keep serving it. They eventually will turn that service off and you won't "own" it.

With discs Sony can't revoke your game like with digital. Doesn't matter if they banned your account. Disc still works for you and whoever comes to gain possession of it.

Plenty of games are fully playable in some form of physical media. In fact, the vast majority of games I have purchased in the last year have been fully playable physical copies. Just because there have been several examples of shitty business practices, doesn't make it a good idea to just give up. There are several massive reasons to die on this hill as others have already outlined in their comments here. Owning the shit we buy, keeping game prices down by giving consumers choice, preventing Sony from giving themselves a monopoly, game preservation. All of these things will be severely damaged or destroyed if we do not die on this hill. If you want to pay less for your games, own what you buy, and preserve games, it is imperative that we stop Sony.