This phenom has been happening before MADD, but you are correct in that there is more than homosexuality behind why men don’t bond like they used to do.
I think most of it, upon further reflection, can be traced to the rise of feminism. There used to be a time when men could be men amongst each other. They could tell dirty jokes, get jokingly physical with each other, hold each other accountable for failing to uphold and practice the masculine virtues. Society allowed males to learn these things from the crib, through males clubs like Boy Scouts, and through interactions with each other at work. There was a constant reinforcement of what it meant to be male, throughout history. However, just try to act like how men should act in society and just watch the criticism and rebuke flow.