Those are red herrings and very different from EQ.I sharing my experiences.
I gave some extra advices like the polarity and the phase, that usually are not shared, when the topic is the de emphasis curves for stereo records.
You can say that I should lower the vta for Mercury records and that is the right thing to do, but for me it is not right, than so what, is it a false statement?
Its true that various labels have a different 'house sound' but its incorrect to say they used a different EQ other than RIAA.