I had customers ordering AR pistols as far back as the Federal AWB era, without braces, as they had not yet been invented. At the time, we really only had access to rifle length extensions as “rumor had it” that carbine extensions constituted intent to install a stock, as well as the fact carbine stocks and buffer tubes were already relatively more rare to find and were themselves a hot button issue (we had to pin stocks to tubes to become fixed length, since telescoping stocks were one of the “points” towards a prohibited Assault Weapon…), and pistol length buffer tubes were as rare as hen’s teeth… AR pistols of the era weren’t terribly short, overall. But people bought them…
Thereafter the ban when braces were invented, traction was relatively slow to build, since the determination in the field was that “shouldering a pistol remade a Firearm (capital F, as in an NFA Firearm, aka, SBR),” but again, folks were still buying and building AR pistols.
The updated conclusion that “a firearm was not made or remade by shouldering a brace” coupled with the advent of social media popularity of “Insta-gun accounts” duly accelerated public interest in AR pistols, which is largely indicative that a LOT of folks intended to shoulder their pistols as they would a rifle, but the law recognized them as pistols, all the same.
With the latest conclusion, again that “a modification which can be used as a stock constitutes a stock,” there are still folks building and buying AR pistols without braces - the luxury today being greater availability of AR-ish designs which integrate their recoil springs into the upper receiver rather than the receiver extension, allowing AR pistols to have a form more akin to MP5’s and AK’s to make a much more convenient pistol.
And even within the current ambiguity surrounding whether the pending lawsuit will repeal the proposed and cast determination, or will it stand, folks are still buying and building AR pistols, with and without braces…
Naturally, there do exist ~3/4 million registered SBR’s in the United States, and reportedly there are over 4 million AR pistols already present in the US, so among an existing market base of ~5 million and around 3,500 new firearms owners being born EVERY SINGLE DAY, eh, it makes sense that sub-16” uppers and barrels continue to be sold.