Asking "do you agree with my opinion X" feels good in the moment: the other person is more likely to agree, as agreeing feels good.

Asking "what do you think" without pre-supplying your take is riskier. But it's worth it, because you get more information, which is far more valuable than feeling good in the moment.

Opinion doesn’t matter if they don’t know what they’re building and what’s their vision.

Agree… But when we’re building something we need to believe in our product. Otherwise there maybe a point where builders will abandon the project which happens most of the time in Crypto. 

For Example: Vitalik must have believed in Ethereum’s potential before us.

Not everyone is a visionary builder. Often you really do just want 5 data points on whether A feels more right or B, or if there is some C you have not considered.