WoWProgress shows a warrior that's gotten to ~86.
I'd suggest refining your strat, gems, reforges.
So is your argument that because a few very skilled warriors have been able to make it well into endless, then the proving grounds are well designed? Even though the percentage of warriors in the rankings for tank are almost nonexistent?
My argument is that it's possible and that, while you're free to offer suggestions for how it can be improved, you should also make do with what you've been given.
The amount of warriors ranking is certainly less than monks and DKs, but they're still ranking. So I would suggest working on your strat, gems, and reforges... unless you would prefer to quit where others have succeeded.
I would point out that you're complaining about gold, and not even endless.