The terminology confusion was too difficult to resolve.

"REST" became associated with a good API design, so when people were told their API isn't a real REST, they interpreted it as having to implement more of Roy Fielding's vision to make it a really good API.

"Real REST must be self-describing hypermedia!" sounded like "you have to add more hyperlinks and delete your API docs", which of course didn't make any sense when you already had a thick RPC client (and RPC may have been the right architecture for the API).

"RESTful" was too similar to be a term for the opposite of the original REST, so it was too easy to interpret the issue as a technical criticism of "RESTful" being weak and falling short of fully-featured ideal "REST" rather than a terminology problem of the same term used for two valid but opposite architectural approaches.

The other term used at that time was AJAX ("async JS and XML"), which made even less sense for the "sync PHP and JSON" APIs (Node.js didn't exist yet).