> The proposer of the idea needs to nurture it and part of that is defending it.

Some people are focusing on the first sentence, but I think this part is key. Obviously, if it's a good idea and you're putting in the work, that's probably a good direction. Critique is useful, defending an idea can help prevent you from being blindsided and help to hone your vision.

One of the things a lot of people seem to struggle with is knowing when it's worth it to keep going and when to let go. When working on something, there can be a lot of people coming from all sides saying, "this won't work," "this will work if you just stick with it", "actually, you're just missing X." There's a lot of noise, and the pushback can be fairly cliche at times.

Sometimes, things like you've mentioned like lack of experience will block them. But, depending on how strongly somebody feels about a concept, when they don't necessarily know if it's a good idea, they may just nurture it and see how everything plays out. It's okay if some things fail.