If you've ever had trauma, especially recent, you'll appreciate well done content warnings. You don't want the dramatic plot twist to happen to be exactly the topic you've been trying to avoid so that you can slowly get better.
If you've experienced a certain kind of trauma, it's not a matter willpower. It involves a loss of control over one's emotional response and thoughts which can be triggered by things that relate to your trauma.
Don't knock on content warnings just because they lack rigorous evidence or because "trigger warnings" became the butt of jokes for a while. They have a genuine utility.
Teaching people to not let emotions get to them, and offending them to build up that immunity, used to be a normal part of life. I wonder what happened.
The problem is they are explicitly arguing that all of our best science is that trigger warnings are counter productive for getting better. Just a quick google search of 'scientific support for trigger warnings' will get you all sorts of meta analysis, RCT results, etc. on this. At best they don't seem to actually do anything, and at worst, they actively impede your ability to get better.
That doesn't mean it's a matter of willpower, but it does suggest that avoiding your triggers or trying to use trigger warnings to prepare you for dealing with them provides no benefit. Your use of the word avoid pretty much sums up the core problem here - on a personal enjoyment of day to day life level, avoiding your triggers makes perfect sense. On the long term healing and not being traumatized by them level, you don't want to do that. (Edit: This isn't to say try taking exposure therapy into your own hands and just surround yourself with the stuff. None of this is a replacement for guided therapy. But specifically going out of your way to avoid these things is 'avoidant behavior' and is pretty much universally recognized as being a bad thing when it comes to dealing with PTSD etc.)
That being said, I believe everyone should be able to disclaim what they want and that people can choose how they approach their own self-care, even if it isn't supported by the science.