Distributed control is still useful. It makes it incredibly expensive to try and tamper with the results.

So the important part is the visibility of the blockchain, not the distributed control? One could still verify whether tampering had occurred?

In my forum project, I use blockchain-like elements in the sense that when one replies to an existing comment, they include its hash in the reply text, which is then PGP-signed.

It is not a chain, however, more like a tree/web. And anyone can inspect the tree and re-verify its validity.

What is on the tree, however, is decided by me, the webmaster-operator. If there are troll comments that I want removed, they're gone. But I cannot forge something by another user, because I do not have their private key.

And anyone else can fork the forum and append to the tree in their own way, and I cannot stop them.