Having grown up watching rating systems become completely useless (remember R-rated movies? If you've watched any shows on streaming platforms lately you know that the ratings have flown away). I can remember when it was shocking that they showed a naked butt on NYPD blue - compare that to the practically pornographic nature of TV shows today and we can recognize that the internet has changed things.
All that said, I think that trigger warnings attempt to moderate some of this. The internet can be an absolute cesspool of debauchery and violence and sometimes things come out of left-field and can leave you feeling anxious the rest of the day. If you'd prefer, try the term "content warning" - I really appreciate it when articles have these. It allows me a moment to reflect on what I'm about to consume. Sometimes the CW is enough for me to stop and ask how I feel and realize that no, I'm really not in a good place to consume this right now.
What's interesting is that my comfort level ebbs and flows. There are days when I can read books that have horrific violent scenes and there have been months in the past year when the most I could stomach was light comedy. I believe that rather than your take, that the trigger warnings treat readers as if they "don't know how to take care of their emotions" - it does the exact OPPOSITE. It gives the power to me to decide if I'm in the headspace to handle it. Personally, when I see that an author has offered a content or trigger warning, I feel that they are showing compassion to their readers, and I feel seen.