It seems as if there would be quite a few fine guns that end up not being terribly popular in the various competitions due to their particular "peculiarities".
Yeah, that's something I wrestle with from time to time. Surely the differences between the absolute qualities of the many various guns can't be so extreme that four or five models are really THE universal best guns, but you'd think so from watching most practical competition.
Yes, a polymer striker-fired gun that holds a fair bit of ammo has very discernable benefits. And the popular models have a LOT of support both from their manufacturers and the aftermarket. That's huge.
But it is a real truth that the competition world sort of has things narrowed down to a few variations on a formula (sort of like Indy cars, I guess) and if a design is very different at all from that formula (and doesn't have the support) it just isn't competitive. So, outside of the revolver and 1911 classes, you end up with Glocks Glocks Glocks, and lots of M&Ps taking up maybe 85% of the field), a few xDs (maybe 5%), and then a sprinkling of CZs & clones, Sigs, Hi-Powers, and M9 Berettas together making up the penultimate 8-9%. After that, there will be the lonely "alsos". One percent or two that will be a Ruger of some type, Non-M9/92 Berettas, FNHs, Steyrs, Walthers, Taruses, HKs, old generation S&W autos, and so forth.
Certainly someone could grab their HK or FN or Ruger, put together a decent kit to go along with it, and really rock at least their local match scene. But it sure doesn't seem to happen often/ever. And that leads to the (possibly false) self-perpetuating idea that they just aren't for the serious competitor. I think a lot of guys coming up see the big names move toward those most common thee or five designs (even making late-career shifts in platform) and assume that if they put their thousands of hours of practice in with their secondary brand gun, eventually they'll hit a point where they're being held back by that gun and will have to switch to the more well-suited Glock or M&P or whatnot.
(For most of them they never really will pursue their skills development that far anyway, but why start down a dead-end road, you know?)