I was one of those telescope making guys, years ago.
I tried the hobbing with a tap, but wasn't overly pleased with what I ended up with. You are correct, a large tooth number with a fine pitch tooth is going to average out a lot better than a small gear with only a few teeth, for the reasons I described.
Amateur astronomers taking astrophotos fully expect to sit at the guidescope and make fine adjustments to keep a star centered on a crosshair. So if their large gear is plus or minus a tooth or two, it really doesn't matter to them. Inherent inaccuracy of the gear is discounted by too many other factors, like the aberration of starlight and atmospheric refraction, so even a perfect gear still needs to be actively tweaked to keep the scope on track.
For a rotary table though, a person is going to want a fairly strong tooth, and this precludes cutting the thing with a thread tap. And most certainly, he will want a common 40, 60 or 90 to one tooth ratio, not a tooth more or less. And he would like the gap to be the same between all the teeth without a catchup glitch between #40 and #1
I built the first rotary table that I ever owned, using a standard Browning worm and gear. I had enough fun building all the rest of the table, I was quite happy with the results, using the commercially made gear.