RE: https://glammr.us/@spagotto/116024075867770850
As another commenter pointed out, this is likely a change made in response to scraping of metadata (see: OCLC lawsuit against Anna's Archive, etc). However I suspect it would be trivial for a scraper to create a WorldCat account and then proceed with harvesting metadata from the site. Maybe this change is just to establish the context that the metadata is not a free resource for anyone to access online?