I can believe this at some level. Piano tuning is a world of compromises. This is true, although much less-so, even if tuning for a specific performance/key as happens for professional concerts. When tuning for general use the compromises are significant for sophisticated ears (not mine, though - I’m pretty insensitive to the nuance)
But it seems that the results obtained by “ear” of the best piano tuners could be measured, codified and reproduced reliably with professional quality instrumentation. Even my iPhone does a decent job of being a tuner, I can’t imagine that something high-end couldn’t be truly excellent, once calibrated by the work of the genius tuners.
