As someone who is lucky enough to live in Germany..
We have a hell of a lot of WBs, naturally. We also have 'tinkers', Iberian breeds, Friesians...
And we also see a lot of the best of all breeds.
You point me out a Friesian or tinker in the upper dressage levels and I will eat my hat.
Any horse is capable of anything, but people have spent DECADES producing lines through careful breeding to excel at their certain disciplines.
If, as a dressage rider, I want to plod around and dabble in anything, I will look at any breed, but a suitable manner and training.
If I want to hit the higher levels, I do not go any buy a tinker!! They are not bred for that purpose.
(On the flip side, you couldn't get me to touch the Jazz/Pilot lines :P)
The ridden horse didn't pop out with the correct confo for what people wanted to do.
If I see a heavier horse at a dressage competition, I think 'wow.. rider must be good, horse must have some talent.. but very unlikely to win' because against a WB who has been specifically bred for that purpose?? No.
There is /always/ going to be breed snobbery. It gets as petty as bloodline snobbery too.
My advice is.. you have a horse, ride it to your best ability, and her/his too. If we spent so much time worried about people's opinions on our horse's breed, saddle, numnah, stables.. it really would be a sport for the rich only.