@sirwolfeye
It fulfills a common introverted beta male dream: that the teasing and flirtation from an extrovert, attractive and popular girl isn’t just for fun and out of boredom, but she actually is interested romantically or just develops feelings over time. In reality this never happnes (it’s completely unnatural to build attraction this way for a normal girl) and the girl usually loses her hyper-interest in just a few days, sometimes weeks and then either stays as a good friend or not (if the male tried to confess and was inevitably rejected).
A friendzoning Nagatoro would be awfully realistic and we don’t need manga for that, real life is cruel enough.
Same with popularity of the tsundere type of character (which doesn’t exist in reality). Invented by George Lucas, it is the realization of a dream that the rejecting female actually just pretends out of shame, which is bizarre but sexy and cute at the same time.