I don't want to insult you, but I had to re-program myself in order to accept TDD and newer processes and there are a lot of systems out there that weren't written with testability in mind and are very difficult to deal with as a result. You are describing a prototype-until-you-reach-done type of approach, which is how we ended up with so much untestable code. My take is that you do a PoC, then throw it out and write the real application. "Build one to throw away" as Brooks said back in 1975.

I get where you're coming from, because I'm about a decade behind you, but resisting change is not a good look. I feel the same way about all this vibe coding and junk--don't really think it's a good idea, but there it is. Get used to being wrong about everything.