But anyone can create infinite ledgers and create their own entries on those ledgers all day. Snowflakes are unique too, but that doesn't mean any of them are particularly valuable.
What matters is who issued it. If you buy an NFT of a Tyler Hobbs painting it's valuable because it was minted by Tyler Hobbs. That one is on one ledger only and even if he himself starts putting it on multiple ledgers it would devalue itself naturally.
Sure, if you're going to argue from a position of economic nihilism that the only value anything is determined by what some idiot is willing to pay for it, then you can call that NFT valuable. That isn't much of a discussion though is it? Since I could also call Beanie Babies and tulip bulbs valuable. If I give my friend $100 for a red paperclip and he gives me $100 for a green paperclip could say those paperclips were worth $100.
I'm not saying anything about the intrinsic value here, only that the blockchain indeed provides a way to make something digitally actually scarce. Is it valuable in itself? Definitely not.
It's all a social construct.