You technically don't own games. You own a license to play them. This has always been the case going back at least to the 80s if not before (first time I noticed this was Dr. Mario on the NES when reading the manual as I'd just learned how to read). If your disc is ruined you can contact them for a replacement disc since your license was not destroyed or forfeited. This is also why you are legally permitted to make one backup copy. Saves them from having to do the replacement themselves.

At the rate streamers are tossing content away forever I wouldn't risk it by tossing these.