I hate when websites pull those kinds of tricks. That's just the kind of website I won't join. I'm mildly curious to know the answer, but not enough to register at their site. And I'm not sure I would believe what they have to say anyway, if they're the kind of people who stoop to deceptive practices to get me to read their site in the first place.
When I clicked the second link in the article excerpt (the one that says “fool.com”), I was able to read the whole article. I have never registered at the Motley Fool website.