Having used the Noct since 2017, and a couple of 50/1.2 before, I have slightly different views.
As I mostly shoot static subjects with MF lenses, aperture is to me the synonym of DoF. Everything else is taken care of by the wide ISO range provided by the Df.
The Noct provides me with a full range of DoF, according to circumstances. f/1.2 is mostly irrelevant at minimum focussing distance (unless you want everything to be unsharp); f/2.8 seems the bare minimum.
At a distance, subject isolation benefits a lot from f/1.2-f/1.4 (other, similar case: the 105/1.8 AIS wide open also allows such tricks, but bokeh is not so good). When I need more sharpness and DoF, f/4-f/8 is also available and usable with the Noct, despite some field curvature. Besides, the Noct has more barrel distortion than classical fifties, but it is easily corrected if need be (i.e., rarely).
Bottom line, the Noct is a fine all-rounder if you *also* need high subject isolation, but it remains an all-rounder all the same, also because it is rather small and light, compared with contemporary monsters. I can shoot all day and not swap lenses all the time. The Noct is sure not perfect; its main drawback however is price but even so, my non-financial ROI is significant. I wonder what would have happened if it had been produced in higher quantities using machine-grinding for the aspherical front element...
Of course, given the present market where chart-shooters have the say, the old Noct is doomed and will remain a collector item, in most cases.
I'm happy to have found Mr. Rörslett's website, early in my digital photography "career", helping me stay away from charts when considering actual lens usability.
By the way, on my fourth and so far last trip to Japan, I decided to take the Noct with me (together with the Zeiss 25/2) and did not regret it. Another similar setting I frequently use is Nikkor 28/2 + Voigtländer 58/1.4.