It’s normal technique taught for public speaking and vocal recording. In some contexts it’s called the command voice.
Businessy settings have read all sorts of make friends and influence sales bull into it. And it does tend carry a lot of sexism and judgement related to women’s speech.
But at base it’s more about performance technique and how sound interacts with a room or sound equipment. Lower pitches tend to carry better in a room, within reason cause too low and words become indistinct. Higher tones provide clarity, but come with more restricted pitch and don’t carry as well. Mids split the difference, carry fairly well while clear. But too restricted become monotone.
Language tends to start low and sweep high, or start high and move low, both across words and across phrases or sentences. With low to high being more common in English and a lot of Western languages. But most people tend to talk naturally in the mid-high portion of their range. And there’s a natural tendency to shift that higher when you’re attempting to be heard. Higher pitches take more force to produce, which feels louder. But volume doesn’t come from pitch, and you’re getting less for all that force at the extremes of your range.
And in terms of performance you need to use as much of your vocal range as you can without straining to avoid sounding monotone. You can’t go too high or low, cause you’ll strain and your voice will break.
Since most people are starting relatively high, they’ve got less place to move up with the natural rhythms of speech before they sound strained, thin, and their volume tapers off. It also has impacts on breath control down to how much air you’re pushing at the extremes of your range.
So one of the base strategies is to teach people to start lower than they normally would, and to avoid raising their pitch in an attempt to be louder. Since that’s not what makes you louder. The idea being to sweep through the mids, with touches of unforced highs and lows. It’s less about pitch relative to other people, than it is about relative to yourself. How much and which portion of your range are you using. And how.
I don’t know from music, so I can’t tell you how any of that relates to singing. Not the kind of audio or production work I’ve done. But this is pretty normal, maybe she read a copy of some management guide, maybe she’s responding to a sexist environment, maybe it’s part of a con. But it’s just as likely she took a public speaking class in college, or did some community theater.