The recipe instructions are worthless after the part where it says "and then pitch yeast." Most extract recipes are formulated for the beginner who wants to drink his beer ASAP. Take the Mr Beer instructions for example. 1 week in primary, 1 week in bottles, then drink! Woohoo, I was really hoping that my Dry Stout would taste like beer flavored club soda!
There isn't really a point of no return in primary. There does come a time when autolysis is a threat, but 1-2 months isn't going to invite the big-A boogeyman as long as fermentation temperatures are reasonable.
You are correct that the only point of using a secondary is to get the beer off the trub to help it clear. The reason secondary isn't 100% necessary is that given a long enough time line (1 month-ish) the yeast will clean up after themselves, and all that sediment will settle into trub. In reality, a long secondary vs. a short primary and a moderate secondary are the same thing.