True enough, but in the early days everyone was using P2PK, meaning that these coins will eventually be reclaimed and reenter circulation if/when the ECDLP is broken by quantum computers.

There are undoubtedly hundreds of thousands, if not millions, of coins which are effectively lost, in which the owner has sent to an address with no known private key, lost/deleted/thrown out their wallet, or something similar. But there is zero way to prove any of this, and even the famous ones like the guy who says he wants to search through a landfill for his hard drive may simply be lying. I personally lose all my private keys in an unfortunate boating accident several times a year. We also have no way of knowing that Satoshi's coins won't suddenly move tomorrow.

So yeah, the provably lost amount of bitcoin is significantly smaller than the probably lost amount of bitcoin. And if you want to burn some bitcoin, far better to do it to an OP_RETURN output than a burner address.