Mature tag is always a sensitive, yet interesting topic to talk about.
For your reference, I am from Indonesia, a country in South East Asia (some people actually asked where this is so I put it in). For your reference, I am a fully adult (25+).
Whatever I said in here is personal experience and contains personal preferences.
First, I think TWs are needed. I am quite open to those topics (sex, disturbing gore/sadistic, religion-related or cults, dark psychological), but I know some people are not. Like you said, it may be connected with their traumas, or they just simply not comfortable with it. I understand your concern about blurbs, but it is best to not give traumatic experience to readers. Let them know what might happen. If they are not comfortable, let them leave.
I still remember got caught playing a sadistic visual novel by my parent and she hates that game until today because she thought it might influence my way of thinking. I was a teenager back then. And no, it did not influence me to do anything haha.
Age differences makes the difference in way of thinking. Different technology and knowledge shapes different way of perceiving what is acceptable and what is not. 20ish would always be different than 30s, and so does with 40ish, 50ish, and so on. I have different perspective with my parents about a lot of things, from work to perceiving stories, movies, arts, news, etc. A real example is going to psychiatrist. I felt back then I really need one, but my parents insisting I do not need one --it is not that hard until you need one. In the end, I did not go to any, but recovering by my own is really hard and no, they did not know. All they know is why would I resign and move to a new job with lower salary.
Writing style, as in, being explicit or not? I do not quite understand what you mean with this.
Some sensitive issue is LGBT (I am not opening any debate to this, just stating) and religion-related in my country. Some are actually okay and enjoy, but from what I know, we enjoy in silent (like me). I am not opening any debate. Same sex marriage is illegal here. Religion-related, which actually comes from a real one also a very sensitive issue which heavily offend some people.
Well I never really write anything that explicit. Maybe a bit killing scene (mine in fantasy, I might describe a murder or a fight leading to it. Stabbing a few times to ensure the death?) But there was one fantasy novel series, which actually inspires me to write, set in a fictional world and it created by some authors (like a big mega projects), and somehow they were fine to publish back then. They have this explicit illustration where one of the characters' arm got cut and still have to walk, side by side with MC. I bought it when I was 15/16 and it is not mature tagged. I bought it via bookstore, offline and a big one, and I bought it by myself (without my parents). Either it was not that famous back then, or fantasy is just a kinda unpopular genre so not much people actually cares, I dunno.
But still, in the end, Imo TWs are needed. Better prevent before got complaints/reported or something akin to that...
This is very long omg