That is indeed something it does.
But it also gives you the assurance that a single entity can't print unlimited money out of thin air, which is the case with a centrally controlled currency like Worldcoin.
They can just shrug their shoulders and claim that all that money is for the poor and gullible Africans that had their eyeballs scanned.
Sure, but the inability to do that when needed is also a bad thing.
Also, single world currencies are (currently) a bad thing, because when your bit of the world needs to devalue its currency is generally different to when mine needs to do that.
But this is why economics is its own specialty and not something that software nerds should jump into like our example with numbers counts for much :D
When and why would BTC or ETH need to print unlimited money and devalue themselves?
And the answer to that is all the reasons governments do just that, except for the times where the government is being particularly stupid and doing hyperinflation.