Most programmers are notoriously bad about estimating anything - ship dates, time to investigate bugs, time to close bugs, time to implement features, complexity, etc, etc. I wouldn't blindly believe a programmer about a tool increasing productivity by __ %. I would listen to their argument first, and look at their experience. I would believe them if they have made good decisions in the past, or if they were a senior/experienced person who understands these nuances. In any case, I hope you agree that there is a spectrum. Because disagreement is not about "incompetence".

Unfortunately, you just described 99% of employers. "Just quit" isn't an answer when there are no meaningful alternatives. Business views SWE/tech as a cost of doing business rather than an investment.