It isn't just PADI ... NAUI has exactly the same standard ... 20 dives to start DM and 60 dives before you complete it.
I've only ever met two people who I would consider to have demonstration-quality diving skills with that many dives, and neither one of them had yet developed enough insight through experience to have been trusted with students or newly-certified OW divers. Fortunately, they both knew it.
There's a thread in here somewhere about a local (to me) instructor who was so inept she couldn't even put her own fins on without assistance. Even her OW students were wary of her. She's a classic example of someone who became an instructor by going from class-to-class-to-class without ever doing any real-world diving, and got her instructor certification as soon as she met the minimum requirements.
But, as I mentioned above ... this isn't just a PADI issue. My own agency uses the same low bar ...
... Bob (Grateful Diver)
It has been a while but I thought that NAUI did have higher standards, it's shame when competition drives standards down rather than than the opposite.