I'm reminded of a similar situation - many states have laws requiring vehicles to have their tires covered by the fenders, to prevent debris from getting kicked up onto following cars.
And yet many states have owners of 4WD vehicles with large tires exposed which throw mud all over the exterior and behind them, anyway.
No enforcement.
Same for muffler laws, the motorcyclists in my town are under the impression that loud pipes save lives, and the police do nothing about their open exhaust. But a hot rod or motor vehicle with straight headers gets pulled over.
Sure, there is some enforcement, it's selective. And not every range even has an RO enforce local rules, or wants to act as an employee of the ATF on an issue that is far from decided.
This is far from over.
Ten years ago if you had built an AR pistol and then pinned a long flash hider on it to make the barrel 16"+, it would then be a rifle. But if you removed the flash hider, woe unto you, it was redesigning it as an SBR and you better have applied for the stamp or face prosecution.
Now you can - because the ATF was taken to court on that issue and lost. A firearm that could have both a short and long barrel on it, with either a pistol or rifle stock, which could be changed back and forth was deemed an exception, and the trickle down rule is that now, if you build the AR as a pistol first, you can change it back and forth.
And of course, no, nobody recommends building it as an SBR and then going out in public. Not without the stamp. Nobody publicly advocates breaking the law, especially in print on the internet.
On the other hand, what enforcement will there be? As said, the ATF isn't hauling VFG violators into court. I won't expect brace users to be arrested any time soon, certainly not in any significant numbers.
Maybe one guy? Ruin his life with legal fees? Lost job, family estranged, oh noooo, the horror, the horror, who could stand up to that? The poor guy needs to be put on suicide watch because his life will be ruined!
Life happens. Accept the risks or don't play the game.