TW’s are a perfect example of controlled exposure. The “control” aspect is just as important as the “exposure” part. Re-traumatizing someone can result if you just expose them to upsetting material while still robbing them of agency.
No one is arguing for required TWs here. And providing TWs, when an educator choses to do so, is not onerous. This is not some cookie that every student is going to be grabbing for. Trust me. I hand out a form asking students for any TW’s they want to request, if any, and most semesters I get exactly ZERO requests. Your slippery-slope concern that everybody’s gonna want a TW for their own specific thing is not rooted in reality. There is no reason for someone without a trauma trigger or other mental illness trigger to want one. And even if every person in the class had their own unique trigger, adding the relevant TWs to my class materials for every person would talk half an hour, tops. It’s worth it.