Cold approaches are so lame. Beyond bothering women and making them feel uncomfortable, it's completely inefficient and you devalue yourself as a man.
Say you approach a random attractive girl on the street, no other context, what are the chances you actually match personalitywise?
What about all the girls that could have been a match, but rejected you because you chose to be a douche/creep by approaching them purely based on looks?
You could argue you are a great guy or whatever, but because of past experiences/other dudes constantly hiting on her in the same way, it will be an automatic no.
PUAs argue that this is a numbers game, you ask 100 girls, maybe one or two will date you. How humanizing...
An other argument they have is that it'll teach you to deal with rejection. So you creep out a ton of girls simply so you can do your small experiment.
It is important to learn how to deal with rejection, yes, but you don't need to completely humiliate yourself to get there.