<offtopic>Since when does medium require an account to read blog articles? Don't think that used to be the case, or are my memories gaslighting me? I'm interested in this article, but don't wanna create an account for medium.</offtopic>
Edit: OK, I just answered my own question. At the top it says:
"You have 2 free member-only stories left this month. Sign up for Medium and get an extra one"
You only get ONE more story to read after signing up? That's very misleading.
Lots of sites would like to make the paywalls immediate, but they won't get ranked highly on search engines if they don't show the article's content to a web crawler.
So the usual approach is to load the content, then hide it as quickly as possible if an unauthorized human is viewing the page.