Sure at a big company. But this advice is targeted to engineers who want to start their own company. Its unlikely they can even afford any of the layers of cruft you are talking about.
If this was advice for starting some new initiative at BigCorp I might agree with you.
The need to build before selling is more critical for start-ups or single person gigs or consulting, because in those situations you don’t have existing stable revenue streams to use to absorb financial or reputational losses that come from underestimating implementation time or cost and failing to deliver sales promises.
If it matters to build before selling in a mature company, it matters even more in a start-up / solo business / consulting feasibility discussion / etc.
If this was advice for starting some new initiative at BigCorp I might agree with you.