The only thing wrong with it is that you generally have to have a Facebook account to read Facebook content, which means you have to give them your real name. It appears that this month Facebook is allowing people to read this particular post, but they aggressively put the sign up wall wherever they thing it will generate the most conversions. You certainly can not see John Carmack's past posts without a Facebook account. Facebook is not the open web.

Technically you can violate the ToS and set up a fake account, but that's a bit of an inconvenience