This all went completely awry when it became accepted wisdom that making someone feel bad is a form of harm and protecting against meanness has value. I could accept your right to be a degenerate as long as my right was equally defended to look you in the eye and call you a retarded faggot and laugh about it, but if the tolerance only goes one way, it's not really a principle. If I am expected to behave according to your standards even if I don't agree with them, then the same must be expected of you in reverse, regardless of "context", because you have no standing to assert that your line for what's acceptable is more correct than mine.
This is why virtue signaling and credentialism tend to go hand in hand, to look to the external to validate your own set of values as the correct set of what should and shouldn't be tolerated by everyone. We both possess the ability to wield rhetoric and statistics to "prove" our own view is objectively correct for all, so aligning with the dominant power structures lends more legitimacy by giving your angle social backing. This lets you maintain the stance that you are above the petty human tendencies of deciding your views based on your own subjective perspective, and frame what you desire as what is actually best for everyone whether the others know it or not.
The final problem I have with "live and let live" is that everything is intricately connected, unless you live in total isolation in a sealed vault, all of your actions affect other people. It's myopic to only look at the direct impacts of your actions and ignore the indirect ones that will come to pass years down the line as a result of a subtle change in your relationship with others or a gradual Pavlovian alteration in your own thought process and thus future habits. It's hubris to convince yourself these distant effects will not happen or won't matter. The evil of this mindset is that the only way to understand this and still justify it is to sincerely believe that nothing ever matters except your own happiness and any obstacle to that is to be done away with. There's a great irony in these types using deep detachment to rail against "social constructs" as something useless and detrimental, seemingly unaware that the entirety of civilization itself is the ultimate social construct and every attack on the concept of a social construct is a chip against the fundamentals of all society itself, aimed in the direction of pushing people back to brutal Law of the Jungle natural order, the system in which raw power itself is the only good. Every system of moral thought that's ever produced an empire or a stable civilization made personal sacrifice among the highest virtues, every society that's hopelessly mired in endless corruption century after century emphasizes pursuing only one's own needs and accepting injustice, and this is not a coincidence.
