Of course.
Now what percentage do? I mean really.
I think it is a little on topic. Esp since we are short on facts and just killing time jawing. Makes the topic broad. Someone else posted somewhere else, that a DM is a guide and that is it. It is a lovely expression of liability avoidance and probably should be said even if not truly practiced. Same as DM should expect certified divers to be competent, even if they got off a floating petri dish for their 10 dive ever after at a 2 year break. How many shops will say, no you can't dive with us until you demonstrate skills in the pool? Or conversely take them diving do nothing about the diver clearly endangering themselves?
Again it is matching real world to how it should be. Divers should be competent after OW and should be fresh on skills when they choose to go diving, but often they aren't. So you have to meet in the middle somewhere.