If you have not experienced X, you should not write about X.
Every author writes about things they have not experienced. This is the nature of writing, of placing yourself into the heads of characters, into the events they have experienced. No one copes with events in quite the same manner, no one deals with shit in the same way as everyone else does. To say that someone should not be able to write about events they themselves have not experienced strikes me as censorship of the worst kind. No one owns events. No one owns concepts, or ideas, or even pain and trauma. Nor the expression of it.
Whether one understands a situation/concept/group better from the inside or the outside is an old, old debate, and one never likely to cease. But telling people they should not even make the attempt, that the way they put their own pain into words is invalid because it is not your way, strikes me as dangerous ground to walk on. Yes, some things should not be glorified, but telling people they shouldn't be able to write about them is not a solution at all but perhaps an even worse problem.
No one is going to write about anything in the same manner, or see the same events with the same eyes. We will hurt each other: we can't not hurt each other. But writing can be an act of understanding, a fumbling toward truths in one's own way. And it seems to me to be a poor and narrow thing to limit others because they do not see the world in quite the same way as one does, to say nothing of deeply insulting to imply that because someone turned pain into a kind of poetry that they never experienced said pain at all.