Well... my take on that is, Harmonic Major is no more "contrived" than any other scale you are currently "OK" with. Harmonic Major, Harmonic Minor, Melodic Minor and all the ones people seem to think are hip are all synthetic scales. They are all arrived at by doing what you just said. You change one note in the major or minor scale or some mode of them. To me, they are just a source of different tonalities for soloing, so it's not that big a deal conceptually.
If you are a musician, who is in a situation where you are expected to be creative on the spot, being aware of more vocabulary is better than not being aware of it. The trick is to internalize the scales you choose to work with, so that they show up in your playing. I doubt anyone is gonna know all the scales the Groot has on that list. But you can be proficient at one, two or three of them and be able to open up a huge range of possibilities.
Again, to me, (and maybe me, only) that's the point. It's not to rattle off scales for the sheer sake of it. If you're not into that as a muscian, then there's no need to concern yourself with it.