I think people who complain about content warnings fail to understand what they are for lol. They're so people can make decisions about what media engage with on any given day to manage their own health. No one is saying that any type of content shouldn't be depicted or is bad or needs to be watered down. It's not the same as other rating systems or anti obscenity movements. It's about viewers being able to enjoy their favorite gory bleak violent reality bending upsetting content when they're completely sure they are in a good headspace to watch it.
Ideally, but usually ratings don't tell you much about what is inside. The ratings systems that existed in the US in the 90s and 2000s when Sopranos was on were still pretty entwined with a culture of shame and moral panic about CORRUPTING THE CHILDREN. It was definitely still related to religion and ideas like "you can't put that on tv!!" or "that song is bad and listening to it makes you bad." HBO was not on regular tv partly for that reason. For Edie Falco's generation, I suspect that kind of thing was much worse and more entrenched. So I think older people equate any warnings about the content art with movements to limit what can or should be depicted be in art.