That's too bad. I invite criticism of my projects, because I want to make sure I'm not fooling myself. Other people's perspective can shine new light on a problem and force you to reconsider the idea, hopefully leading to improved design.
Initial ambitions largely set an upper bound on whole project possibilities -- you generally want upper bounds set pretty high. All projects have unknown unknowns that will reveal themselves, and modeling this kind of meta-knowledge is difficult and perhaps not worth the effort.
So to offer a general counterpoint, it may be a valuable skill to listen to constructive advice including ones poking holes in your ideas. The key is to persevere in the face of problems, as long as they're not obviously intransposable (tip: don't go against laws of physics, e.g. thermodynamics or newton's laws). If those hurdles would come up sometime, it might be better to devote more time early on to overcome them.
But if I'm not actually inviting that criticism, it is neither welcome nor helpful.