There are other real reasons for this happening people laid out, but part of it is that...the prevalence of "kids" media in whatever forms are available is a generational trend that ebbs and flows. Not to say there wouldn't always be something kid-friendly, just how bigger picture trends shake out.

90s parents were bigger on "subversive" entertainment where the appeal was pushing boundaries they'd realistically not want kids in on. But my parents would scoff at a fellow adult watching Pokemon with their kids. This era's been more about legit "fun for the whole family" content like Marvel, etc.