Anthem and the other games you mentioned are online only games, but all the textures, models and so on need to be installed and calculated from the console. If it would just be to access the game, then you would just stream the game, which is another thing entirely.
I'm suggesting the updates can sometimes replace all the data entirely, textures and assets included. Like Halo:MCC had a 80+GB patch, that's clearly the entire game being replaced. I think MK11 on Switch is gonna have 22GB patch at launch, that's probably the entire game as well.
When an online only game has updates that replaces all the content or most of it, the disc is literally just access to the game. Destiny and Elder Scrolls Online comes to mind for doing that.