Topic: The concept of the "trigger warning."

I have just been rather bizarrely re-introduced to this concept in a new way.
I had heard the term used before in reference to psychiatric patients suffering from legitimate post-traumatic stress disorder. As in, those subject to uncontrollable and debilitating "flashbacks."
If they were exposed to material addressing the subject of their traumatic experience - child abuse, for example - this may set off the flashback reaction, and that could place the person in danger (they are often unaware of external stimuli during these instances.) Thus with sufferers of such, it is important to understand what the "triggers" that elicit this reaction and avoid those topics around them.
All sensible so far.
Then there is the standard decency version of this - if a colleague had just been through a messy divorce, for example, it is hardly considered appropriate to gush about how blissful your marriage is in their hearing.
But this legitimate concept seems to have mutated out of control and right into the realm of PC, and I wondered how alexithymics may view this conundrum.
Now, I am told, "normal" people (no psychiatric illness or recent temporary sensitivities in life experience to certain topics) apparently demand "trigger warnings" for absolutely anything that may upset them emotionally, or with which they simply disagree. It is up to everyone else to pre-empt this, and "tag" everything they say or write with appropriate warnings about its content. This allows the individual to filter their world according to their specific preferences, and disallow exposure to anything with which they disagree, or is considered in any way distressing.
This, to me, carries several problems. Perhaps I had a rough upbringing, but I tend to believe that this is just life. It owes you nothing. It is not the responsibility of life to cushion and coddle you. Especially as adults, it is a part of life that there will be things that distress you, that upset you, that you dislike and disagree with, and you will be exposed to those things.Developing the resilience to be able to handle this is part of maturity. Indeed, this is often the catalyst for change that improves the lives of millions of people. If the whole adult world had "trigger warning" so they refused to see it, injustices would have continued unchallenged. At times, the hard things in life must be faced.
However I experienced a certain dissonance with my ethics - on one hand there is the above. That is reality. As an adult, not everything is going to be sweet and wonderful and nor really should it be. Because that is simply not how life is. If it is that way for you, it means you are willfully blinding yourself to an informed awareness of the problems of life; problems that perhaps, with enough support, could be changed. The old "sticking your head in the sand," adage applies. "Trigger warning" these things so you refuse to look at them does not make them go away.
But at the same time, my ethics are closely aligned with non-violence. I do not ethically believe that beings should be subjected to harm, and it is certainly unethical to cause others distress or emotional damage. In essence I don't wish to upset people unduly, and believe it ethically sound to be as sensitive and kind to others needs as I can.
Without an emotional understanding, however, it's difficult to understand where the "line" is. Is insisting that as an adult you must have enough resilience to handle things that are distressing or disagreeable simply unethical brutality, a display of a lack of kindness and sensitivity? Is accepting that no one should ever have to be upset or hurt by this kind of content really admirable sensitivity to the emotional nature of normal people, or a blithe collusion with a socially accepted blindness that weakens character and possibly allows unethical actions to pass unchallenged?
What is your view of this?