Just to head this off at the pass, because someone is bound to bring up exposure therapy: hi, hello, I am someone who has been through exposure therapy (technically Exposure/Response Prevention, or ERP). Yes, it is broadly speaking true that avoiding triggers increases anxiety in the long run. However, one thing that was stressed to me over and over in ERP is that exposures have to be VOLUNTARY to be beneficial. Meaning, just hucking a tarantula at someone with arachnophobia is going to do far more harm than good. Likewise showing them a bunch of pictures of spiders with no warning. However, putting a content warning puts the decision to engage back into the hands of the person with the phobia (or trauma, eating disorder, etc), which effectively turns it into a voluntary exposure should they choose to engage.