First, I would like to recommend
http://www.paulgraham.com/say.html as background for what I object to about political correctness.
Political correctness pushes the idea that the whole world should be trying to create a safe space for those who have had any kind of past challenge. There is a time and place for safe spaces. However the act of encouraging people to figure out what problems they can complain about, then coddling them, makes people more fragile. This has long-lasting negative implications for their mental health.
For example https://www.psychologytoday.com/us/blog/what-mentally-strong... explains what has actually been observed in children whose parents tended too closely to their perceived needs. Similarly therapists have found that encouraging people with PTSD to avoid any reminder of their past trauma actually makes the trauma worse. Instead it is more effective to desensitize them with controlled exposure to the trauma to teach them to be able to handle it.
This gives us some idea of how to create mental health. What are we doing instead? Well, we are teaching a whole generation that the world needs to take care of them due to a variety of past misdeeds. In the process we teach them to be sensitive to things that otherwise would not have bothered them very much. We then encourage them to demand that they not encounter reminders of what they don't like, and try to make the whole world a "safe space" for them. This is a recipe for systemically creating PTSD among people who otherwise would not develop it. Thereby creating the exact condition that we are trying to help. And, having created it, we have motivation to do more of the same so that more people become fragile.
I know, I know. This isn't a popular point of view. It suggests that a large portion of the SJW agenda is backwards. However I believe, and there is evidence from psychology to back me up, that it is right. We should not go overboard to protect people from encountering speech and ideas that they don't like. We should instead make people resilient to that experience. Both for their mental health, and so that they learn critical thinking.