Well, I'm sure that some people (in history) were indeed worthy of a paladin title (as it's defined in fantasy).
However, I doubt that there were entire ORGANIZATIONS of such people... because those individual are very rare. I'd say even rarer then mages in low-magic settings
. I guess that's because being a selfish bastard is a distinct survival trait. No wonder we have very few altruists - they all died out long ago
.
And larger organizations would indeed eventually (and inevitably) degrade to Whitecloak-like ones.
I, myself, always thought that, while Believing in something is good (after all, sometimes its only thing we have), but as it becomes religion - divine becomes 'Human, too human'. Those more interested in profit and less - in morality will get to the top (cause they are more interested in this, and better in manipulation, naturally)... and voila, we have what we have.
And besides, a loose quote:
"Immoral and greedy bastard is much preferable to a fanatic, because while first is more interested in money and may even have occasional pangs of guilty conscience, fanatic will spill oceans of blood with no second thought".
Like, Hitler is a perfect example of a paladin. Just substitute ‘evil orcs’ for ‘Jews and Russians’, and ‘God’ for ‘Third Reich’.