> Ok, but the cryptocurrency industry doesn't actually want "you can only use Bitcoin and Ethereum and only via direct interactions with them, not via intermediaries" to be the message, because then what are all these other projects even doing?

You're 100% correct. The Eth L2s are all incredibly centralized. However most stablecoin transactions (ie payments) don't happen on Eth and it's various L2s anymore and I wonder if the same may be true to tokenized assets (RWAs).