Content/trigger warnings are not about "being shielded from hardship;" they're about not springing trauma triggers or upsetting shit on unsuspecting people (or not causing actual physical harm to people, in the case of epilepsy warnings).
Like, OK, cool, you read Mein Kampf. I don't think that's a bad thing to do, for the reasons you did it. But you did that freely and knowing what you were getting into ("by Adolf Hitler" serves as an implicit content warning IMO). Suppose you were a Jewish student and your history teacher sprung a reading from Mein Kampf in the middle of a lesson with no warning. Or hell, just imagine having "Old Yeller" sprung on you the day after your dog died. I don't think it's babying anyone to warn them about something that could ruin their day.
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.