The same with what you refer to as "Bitcoin NFTs". They are literally treated as arbitrary data by the Bitcoin protocol. There is no script. There is no smart contract. There is no verification. Just arbitrary data.
Arbitrary data and
bought notion, both of which are enough to call something a token. The Bitcoin protocol does not understand anything beyond the currency BTC, but it is very possible for me to invent a concept, such as Proof-of-Burn, and invite people to buy this concept. Money is an idea, and tokens are mere abstractions of money.
However, I do agree that all of these non-fungible concepts are shallow and completely driven by speculation.