It takes a lot of time to do even some of what you suggest above.

Not necessarily. Talking doesn't take much – although finding potential customers might take, if you don't have any particular niche in mind already. The point is to get at least some feedback as soon as possible. That feedback can be then used to guide product development to answer a real demand by customers. Often the initial idea might have some value, but it doesn't exactly nail the pain. The idea needs to be adjusted to fully hit the target. And of course marketing is much easier when you understand what your customers think and why they think that way.