This is the central issue.

You have described the effects of using wholly unqualified people who do not know what they are doing performing business-critical strategic tasks (finding out what users' problems are) without the skills and experience to do so.

The "interview script" you provide illustrates the problem - it's one of the worst I've ever seen!

Although the 10,000 Hours Rule is not scientific, the principle tracks - it takes 5-6 years of focussed, guided practice to get really good at anything.

A professional researcher above the entry levels has spent that time; a typical product manager has not. A PM might as well do their own dentistry or write their own contracts - that, too, is specialist work.

You miss out the crucial "discovery" research from that equation, too - or "market research" as it is traditionally known. Market research is as professionalised as accountancy, with similar nationally-accredited qualifications, and many market researchers have transitioned into UX Researcher roles (in practice, they are almost indistinguishable - I ran plenty of usability tests as a market researcher).

The researcher's role is to find out the problems are and provide a list of recommendations - the attributes of a winning solution.

A researcher won't just tell you the "what", but the "why" and the "so what" - the underlying factors that drive the behaviour.

A professional researcher will never ask the customer what to build next.

The PM's role is to choose which problems to prioritise, and which questions need to be answered.