As I said, it's blacksmithing with Calipers.

The brands and builders who get the heavy adoration here were guys that did just that.
The Taylor Brothers would hold a frame up to the window, sight off a muntin and if there was no visible daylight between the three lines, head tube, seat tube and window framework, call it good to go.
What I am saying is that a good, no, a terrific bike can be built with pretty basic tools and proper skill.
I am leaving out mass produced bikes, like the typical Raleighs, Schwinns, and similar of the period as very different methods were employed, tubes were notched, miters were approximate.
Heck, even for many trusted brands, take one apart after crash damage or even strip it of its paint and the reverence will fade away. Well, not fade, but there is a different appreciation of what went into making them.

Scooper's Waterford gets in my view quite a bit of appreciation as there is no paint, almost all the effort shows. A mistake will show.