IIRC, the PS2 did not download game updates or patches from the internet. The game on the disk was what you played. As long as you had a PS2 and the disk, you could play the exact game you played so many years ago.
With the PS5, the disk is more or less a key that lets the console download the game. Having the console and the disk is a guarantee of nothing in the future other than you can probably play the buggy mess that they packaged up way before the game was done.