Not gonna disagree, just explain my point a little-
I have some small amount of experience from "back in the day" on analog mixers. I recall most having no defined levels to the range of cuts/boosts. Just a zero, and a + and - sign. And a range between. Generally defined by ear.
And I have no proof, but it seemed to me the high and low frequency attenuators often had a little more range than the mid. Maybe.
Either way, in practical use, I wouldn't generally see much utility in using 12, much less 15 dB cuts in a channel strip EQ. Most often, smaller increments suit the purpose IMO.
As far as the number of knobs and frequency ranges, I have seen quite a range of examples.
One very famous example would be the Neve 1073.
This I believe had 3 EQ bands, with the high shelf fixed at 12K, the "mid" was adjustable from what could be considered "hi mid" to "low mid", and the low was adjustable between what I would consider "low" and "low mid" frequencies. Add to this a HP that was adjustable from sub to the upper ranges of LF and you had a highly configurable EQ.
For most uses beyond a bass guitar and kick drum, I saw it configured as High, "High mid" and "lo mid" and the HP taking care of rolling off the low frequencies as needed. So not really a High, Mid and Low EQ. Kind of works out like 4 ranges really.
Using this example as but one "ideal" you can see why I for one find the Mixcraft mixer EQ's limiting for advanced use. As I described in the linked post, I think the high and low have some usability, but the mid has very limited use for me.
An upgrade would be welcome. Add this and an input trim, and a mono toggle and.........
This has all been suggested before. We aren't alone.