Machine code has always been enough.
Which license terms, specifically, prevent me from playing a 20-year-old game on a 20-year-old machine?
I'm just stating the fact. If you want to own software, you need to get the source code. If you don't get the source code, you're paying $10-$60 per perishable consumable, and should be always be aware of that, not deluding yourself about some "ownership".
I own my personal computer software, from the Linux OS, through code editor, compilers, etc. I have the source code. I personally care, so I do own, and pay extra (in time and money) for that privilege and look down on people who don't, as I think they are foolish. I do not care about the games, so the license deal is fine with me. I played the game already, if I really want to play it again, I can pay $5 on sale again.
If you and others care about owning games, or any other software for that matter, demand and pay for the source code. Otherwise you own nothing.