The Utilitarian reason is because we have discovered that the only thing more likely to make stupid, irrational decisions than an individual is a group of individuals when that group of individuals is demonstrating groupthink (which is an important part of the PC culture, but can be found in any grouping of humans of sufficient ideological closeness). Close-mindedness can take even a powerful nation and lead it to intellectual repression, stultification, loss of innovation, and, ultimately, societal defeat (see: Ottoman Empire) because self-appointed mindguards are never quite so capable as they think themselves to be. Quite the opposite.
While the ideological argument (from an American / Lockean perspective) is that Free Speech is desirable because no man has the right to limit anothers' speech or thought absent harm to another (quality of thought is irrelevant), the utilitarian perspective is that we allow free speech not because man is so good at figuring out what is good to believe and say, but rather because he is so very bad at it.
....have you been in a time capsule for the past decade or so?It isn't "ever-more-byzantine." It's really simple. Just don't attack a demographic group. Period. That's it. Just that one rule. Attack ideas all you want, attack political groups, etc., but don't attack a demographic group. If you can refrain from doing that one thing, you will never be on the wrong side of PC.
How about "politely decline to participate in someone's wedding with your goods or services"? That's not an attack. How about "believe that marriage is between a man and a woman"? that's not an attack. How about "Thinking that when you put someone on trial for rape, the evidence should be controlling rather than the accusers' desire to be publicly vindicated"? That's not an attack. How about stating that "America is the land of opportunity" or "all lives matter"? Those aren't attacks But all these things are Not PC, and those who have dared to do or say them have and will be appropriately punished. Statistically true information about immigration and rape culture is attacked for not being PC. That's an indication that we are not using the power of the electronic mob to improve debate by getting rid of bad ideas, but rather to shut up heretics who question the Received Wisdom, regardless of their ability to foment arguments.
Of course not. Most folks don't end up a target and most folks learn to keep their heads down. But if you are Ms America, well, you must be politicized and attacked.... for holding a belief that half the country holds.And, no, I don't think that is at all true that 50% of the population gets attacked by PC.