GOG giving you a standalone installer saves you some effort compared to that, but in neither case do you really "own" the game.

Well it makes it hard or impossible to sell your copy of the game to someone else after you are done with it like we used to be able to do with console game discs and cartridges?

Seems like a pretty big and practical difference to me.

If legislators want to do something good, they could force platforms to allow transfer of games between accounts.

I don't think people are so against DRM, because a disc like that was essentially a form of DRM. They are against an online DRM scheme which could change in the future. I know there were sone disc DRM that could like revoke the disc license, but let's go back before that was a thing to like the Xbox/360 and PS1/2/3 era style.

Just about every commercial software license says the software is licensed, not sold.

Of course the practical difference is in whether you can trust you'll be able to keep using the product indefinitely or have to rely on the publisher's goodwill.

(Also, whether the idea that a software product is only licensed and not sold is legally valid of course depends on the jurisdiction and legal interpretation. IIRC back in the day some people tried to argue that you couldn't resell a game or other piece of software you bought on physical media because the software was only licensed to you, not sold. That argument didn't necessarily fly.)