True! However I trust the wikimedia foundation, and the fact that because it is a valuable dataset there are many copies of it. If they really did restrict access, anyone could spin up their mirror.
Most of the decentralisation arguments seem to rely on some fetishistically absolute version of the world where you cannot trust any single person or entity, and crypto/web3 is the only reasonable solution if that is true. I, however, have more faith in other people, and am fine placing trust—to varying degrees—in others.