I think I somewhat disagree with this. I have always had some decent spin with my throwing style, even though I don't throw all that far, but I can almost always get the "intended" flight out of a disc at 250' or at 350'. What I mean by that is, with the proper spin, a PP Crave will fly dead straight when I throw it dead straight. A newer Hokom Crave flies like -1/1 with a baby S curve both powered down at 250 and at my current max power at around 330-350. I noticed that I am even better at this now that I throw the Glitch. At 100' the Glitch goes dead straight. At 250' it still goes dead straight. More than that and I usually mess something up on my form and it drifts or turns over, but if I can get it clean, it goes dead straight.
I do think there are speeds where this starts to fall apart though. Wraths and Insanities tend to fly true to numbers for me, with the exception of Insanities with higher PLH, etc, which I attribute to the disc and not my form. I can throw Photons and Vanished pretty true to numbers, but start to see more inconsistencies with them. Anything faster and it falls apart for me. But, if you ever watch me throw, you'll probably see why. I get plenty of pop from my wrist, but my pull through is not fast. I've had people comment in the past "how do you get your disc to go so far throwing so slow?" And by far, they're still talking only 300', but it still looks like it shouldn't get that far. Anyway, the point is, I think generating spin on the disc happens in a lot of ways, but proper spin really does get a more intended flight path, regardless of velocity thrown.
I have commented about it before on these forums, but a long time ago I was mostly throwing Trilogy when I first discovered MVP. I loved how the flatter profile felt in my hand compared to the bulkier and more domey Trilogy molds. I took a summer and created 2 bags of my core discs. 8 Trilogy molds in one bag and 6-7 MVP discs. (This was early on when MVP only had a small handful of discs) Anyway, I played several courses with both bags, some of them back to back in the same day, some across different days. What I found was, my scores were about the same each time. I saw maybe a 1-2 stroke difference on average, and it wasn't consistent on which one was which. Since I liked the flatter feeling of the MVP discs better, I switched most of my bag over to MVP with the exception of my XXX and Verdict, which were already flat and fairly thin, and my Wedge, which MVP just didn't make a slower disc that understable at the time and it was super useful as a get out of trouble disc for the wooded courses I played at the time.
That being said, I do think that MVP discs tend to lock onto their line better when given proper spin. But, that doesn't necessarily translate into better scores for me on most courses I play. I've just learned to work with the lines I get out of my discs no matter which ones I throw, and I think that's mostly just preference on what you want your lines to look like. I also think that Fission discs may tend to glide a bit more than their non-fission counterparts, though the recent blends of Fission are so slick and stiff, and inconsistent, I don't really like throwing them anyway.
But yeah, flatter is better IMO, both FH and BH personally. I don't find I lose any distance missing the dome, I just like the hand feel better.