I don't expect the vast majority of people to need Content/Trigger warnings so if only 10% of people are not choosing to watch something that seems perfectly fine. I've seen other posts comparing it to epilepsy warnings and that seems a fair comparison which is probably relevant to even less of the population (just checked, around 1% for epilepsy). It's still probably way more useful than most ESRB or MPAA warnings.
That being said I do believe they are often done in very biolerplate and CYA manners which aren't really helpful.
I was recently pleasantly surprised to see how they could be done very well in the game Date Everything, which has dozens (over 100) "things" you can date, each of which has their own story. Right when you meet something with a potentially problematic item the game says hey, this story will involve sexual themes/stalking/toxic relationship/codependency or whatever. It then directly asks the player: do you want to see this?
I didn't have any issue with any of those, but when one popped up that said it involved animal cruelty I decided I didn't really need that story so I skipped it. What is really great is that the game makes it crystal clear the first time you meet one of these that you will not miss out on any rewards for skipping, no in-game stuff or acheivments depend on this. If you choose to skip it just says, cool, which ending do you want for this character? For most characters you can choose romance, friends or enemies and you just keep going. It's very thoughtfully done. It allows you to selectively skip things which you might be perfectly capable of dealing with it, but hey I'm just playing a silly little game right now to escape from reality so lets keep the darker parts reality out of this.