As I understood it, it's to track ownership of in-game assets, who has the right to use what. But it's all a little above my head I must admit, so I can't be sure.
But isn't that just the same hole pretty much every online and/or "social" game with in-game currency falls into. I don't think it will be long before certain people start selling in-game currency and NFTs for real life money.
Even if it says you don't have to use any currency in the game...well look how that works out in many "Free" to Play titles.
Avatar by MasterRed
Taking an extended break from Sims stuff. Might be around, might not.