the worst conventional wisdom in crypto is:

"blockchains will fade into the background and people won't care which one they are using"

(Exhibit A: there were 6 NFT Marketplaces on Terra chain)

I work for Ethereum at the Ethereum Foundation.

That scenario is a *failure* mode for blockchain adoption:

(1) Because "creating a blockchain" is permissionless, the set of all blockchains will always have widely varying security properties

(2) If people can't distinguish between them, they cannot make good choices

Strongly disagree. No average consumer understands nor cares for the tech stack (i.e. how it works beneath the hood) of their daily used products

I think the implicit error there is drawing an arbitrary line around what counts as "tech" in that sentence.

Forget the word "tech" - average people absolutely do care, and know a lot about, the fundamentals of the critical infrastructure they rely upon.