While true, the only one deciding whether you are granted the ingame usage is still the developer/publisher, so in that scenario you basically just did exactly the same thing as before: a database lookup to check if a player "owns" a particular item. Only this time with a much slower and more inefficient database. Nothing about it being a NFT grants any advantages in that case, the developer can still take it away, ban your account, remove the item from the game etc. because they are still the ones controlling everything. You just decentralized the database entry.