[wmf]

"Cloaking" is a naughty SEO tactic of showing one thing (like an article) to search engines and a different thing (like a login screen) to humans. Google bans cloaking; their punishment is de-indexing. But there is a loophole: showing the same thing to Googlebot and regular browsers with a Google referer isn't considered cloaking. The NY Times also uses this technique.

I can't tell you why you're out of the loop, though.