indeed. a little history lesson, in light of some of some of the above:
looking back, it might not be so clear as to how ANYBODY could not have seen the threadless style taking off like it it did. if you were there, it was a very different story, and not at all an unreasonbale view, as evidenced by no less than shimano missing the guess.
to wit: many of the “advantages” in the threadless design were not actually PRESENT, at the start. the original threadless headsets had very few, if any, real advantages over threaded designs save one.
threadless headsets cut down OEM maunfacturing costs significantly. machines can assemble them, and people have to assemble threaded headsets. for this reason and no real other, the threadless design took off like it did. it was also fueled in part - tho much less so than the money/OEM aspect- by the mountain bike boom, and the craze in that niche for the new, beefy, tig welded stems that came on the threadless bikes. the road market actually held out for a time, but then was swept under ( road bikes were horribly passe, and mtn bikes ruled in these days . . . ), even tho the threadless design still held very little or no advantages at all for riders, and numerous disadvantages.
that all changed with the advent of the carbon steerer fork. suddenly, there was a siginificant advantage in weight to the threadless design - not from the headset, but from the carbon steerer forks they allowed ( you cannot make a threaded caron fork). that was it. with the upper end of the market cemented by all carbon forks turning inside threadless headsets the new standard became utterly unasailable. later developements, like the faceplate stem allowing fast and easy bar changes COULD have developed with quill style stems, but they didn’t and too bad for quills.
anyway - as noted if you are not really all that concerned about a few grams, a threaded headset still does offer as many advantages as a threadless, if you are so inclined. many hi -end makers and consumers still are.
we now return you to your regularly scheduled forum, thank you for coming today, there wil be a quiz in the morning.