“If there are enough votes to pass the bill, how can there not be enough votes to pass the rule? Does the rule require a supermajority???”
No. But just like cloture in the senate, conservatives can defeat the bill by defeating the rule, because as the article said, democrats don’t vote against the rule (though I suppose they could).
The point is to not let these congressmen hide behind procedural tactics, to get legislation passed while pretending to be against it.