This is complete nonsense and sounds like musings of a desperate advocate.
If you want to believe something, you start to accept the lamest arguments.
You'd certainly also want a universal one for conversion, but not for every day tedium. Fahrenheit is nice because it spans the human experience in a nice range (say damn cold 0 to rather hot 100). But that's bunk if you're in context of chemistry where water's properties are far more comparative (0 freezes to 100 boiling). Though absolute scales are always a bit sporky, since they latch to a scale and wonk it sideways (-273 is a silly number no matter what anyone says).
And so on. Scales and units are merely benchmarks. Literally. Pick the right bench for the job and follow the marks.
(Though with enough effort you can make any scale work. Kinda like hammers and threaded carpenter nails.)
Edited; typing on phones ruins grammar.
In practice, it was not quite that simple, because of the half percent error, and wire insulation doesn't follow the same scaling pattern, but it was still quite handy, and much less trouble than metric, where you constantly had to dig out the wire gauge chart.