It's not just the lack of skills (which take time and expert guidance to develop), it's also a conflict of interest: most product managers are assessed and rewarded on the basis of the number of features shipped, which creates a disincentive to learn.

I often see a great deal of conversation about learning, but abandoning a prototype because it wasn't solving the user's problem is regarded as waste, so teams try to avoid doing this much.

What we often see instead is "validation" surveys that feature questions such as "would you buy this feature?", which produce unreliable outcomes and are ultimately detrimental to success.