I've had Arabians for 34 years and never come across this supposedly 'common' problem.
In fact, Arabians are known for being hardy, healthy horses. Of course, I'm talking about the old fashioned, sturdy, little, well bred performance horses, not the tall, willowy Saddlebred wanna-bes they're breeding now.
I don't care what you're being told, any horse who is practically crippled every time you ride them has more than a minor issue. You ARE hurting him if he's in pain after every ride.