No one thinks that they own the copyright to Super Mario Bros. just because they bought a copy. There is no confusion, there are just people who want to rewrite history to pretend that you have never owned your copies of games. they try to equate owning a copy of a game with owning the copyright which isn't the way game consumers have ever thought about it. Have you ever heard anyone say 'I own the copyright to Chrono Trigger since I bought a copy of it'?
Agreed.
Nobody think buying a game means you own the code to do what you want. A lot of stuff has copyright or patent info attached to it. If someone buys an album, nobody thinks they own the lyrics.
The only reason game companies do this (and not other industries) is because people don't care. And nobody gives a shit about reading any archaic 30 page Terms and Service Agreements. Again, something only software companies do. You buy a TV, a car or a music album. You don't get T&S paperwork splashed in your face.
If someone buys a car, but a back page claim says despite paying $50,000 for a car, the dealership can take it back or remotely press a button deactivating it, customers would tell the car maker or dealership to fuck off. For games, most gamers don't care, so for those times it happens, it's not enough to move the needle.
And the reason software companies do this is because it can be easily controlled with digital fingerprints, or internet checks, or server side access. The internet has been the holy grail for software companies. Sell people software without stores getting physical copy cuts or packaging, and internet checks grant or deny access.