So, the target speed for the full flap climb in a 150 would be about 54kts (don't know about the 152)... at which it should climb at least as well as prescribed. How many folks would be willing to pitch for that?
Why would it not climb - see above.. this would be a case where an 'extra 5kts for the wife and kids' would not help. Also note that the prescription is 'at sea level' (presumably standard conditions). High density altitude will really hurt that..
I don't think anyone's suggesting that it's a smart idea to do this, or that you shouldn't retract if in any way possible. Merely that it is possible, contrary to popular belief..