True, however the premise of blockchains is that blocks can't be modified after the fact; only new blocks can be added. So the owner of an NFT does have a mathematically verifiable claim that they were "first" to "own" the piece of content (since on some level, the token is generated from the underlying digital signature of the file) which of course is the primary/sole appeal to paying real money for assets that are by definition infinitely replicable and therefore worth nothing.
Except they don't have proof they were the first 'to own the content'. They might have proof they were the first to own a token holding an address that points to something
currently holding the content, but nothing about that process verifies they have any ownership over it.
I will happily sell you an NFT contract stating that you are the one true owner of anything in the world. Anything at all. Even the whole world itself. You can own THAT NFT if you really want to buy one of it.
I have zero authority to
sell the whole world in reality, but there is absolutely nothing preventing me from selling you a useless immutable digital contract saying that I sold it to you...
I can sell you an NFT pointing to any of my art on my own servers. And tomorrow it can point to different art of my choosing at that same address, because I'm more than a slightly trollish person when it comes to things like that. Whatever you 'buy' as an NFT from me would never again appear at that address, because selling the lesson on what an NFT actually is and does is the only remotely valuable thing that NFTs solve.
Unique tokens are a massively useful thing. I've generated and issued literally millions of them over my career. But they're ultimately worthless in and of themselves. They are scams. Doesn't matter how much anyone selling them believes they're not a scam, they are still ultimately a scam.