They want the people who buy physical for the box in their collection, to buy the game, but they don't want anybody to have the ability to resell the game for a fiver after the fact, because that means someone else gets the game without giving them money instead of buying a brand new digital license at full price.

I'm part of the problem, I've only bought games on Steam (or in a few instances in the not too distant past, xbox store for cross-platform Forza enjoyment), but holy hell does it irritate me that we can't actually OWN a copy of a game anymore.