DLC existed in some form long before digital-only releases existed. We just used to call them expansions, and people used to buy them in droves.
Edit: All those downvoting me clearly weren't alive during the shareware boom, or during EA's early attempts to extort players for the pleasure of having a potted plant in The Sims. This outrage over DLC is just an echo chamber of angry gamers who aren't the target audience anyway.
Phantom Liberty is an expansion. Shadow of the Erdtree is an expansion. Knights of the Nine and the Shivering Isles are expansions. Echoes of the Eye is an expansion. Bad Company: Vietnam is an expansion. All of these amount to a third, to a half of the total game content. We used to buy them, and will continue buying them, because they add absolutely insane value to what you already really liked.
"Exclusive cat content" that can only be obtained through a 30$ upgrade, and includes 3 new costumes, and whatever the hell cat content is, is dlc. This adds nothing of value for us, but lines the pockets of the studio shareholders quite substantially.
Just because the large players in the industry are complicit, it doesn't change history, and certainly it doesn't change the vocabulary.