Surprised it has not been mentioned yet, but mbasic.facebook.com would solve the issue in both articles. I don't even have a facebook account and I'm constantly referring people to the slimmer version. I guess they must not advertise it.
Until I've decided to try it in the Chrome Incognito Mode. It worked correctly, without redirecting to the normal facebook's mobile site.
But after coming back from Incognito, it started working as intended on normal browsing mode too.