Just because someone drafted some pixel art on paper doesn't mean that this must be the final form, and that no revision may ever be done.
And with recorded music in particular: Yeah, a good studio usually has a variety of monitors. Some might be exquisitely flat and unnvervingly detailed, some might be capable of effortlessly reaching big-stage PA levels, and some might resemble common consumer gear more than anything else.
If it works well with all of these, then: It might be considered a good mix.
The Yamaha NS-10 is/was a popular speaker in studios not because it was good, but because it represented a common medium-size bookshelf-ish speaker that people might actually use at home where they listened to music, and it was consistent betwixt different studio spaces.