The full games are not always on the disc these days, and I don't think they have been for quite a while. This is partly why physical isn't and will never be the best way to preserve video games. The paratext itself can be preserved, but as for the game itself other means are necessary.

Oh how I remember when people talked about day 1 patches like it was a slight against the gaming community and now they're just a common acceptance.

It is what it is, right? If we want things to be preserved for the future we sadly have to take matters in our own hands at the moment. We simply can't expect profit motivated entities to provide it. They are already compromised.