The work and technical expertise to setup let's encrypt is less than the work to register a domain, set up a web server, and configure DNS to point to it.

You seem to have missed what I wrote in the first place: They aren't tech people.

It is additional work, and requires additional knowledge.

It was also not available from most of the free web hosts that sites like these used before the https push. So investigating alternatives and migrating were required. In other words, still more work.