Perhaps, but I don't really think so. To access notification categories, you need to long tap the app, tap on app settings/info, tap notifications, and then tap on notification categories. It's out of your way unless you intentionally want to access it, the sort of person who'd be confused by such things wouldn't just stumble on this setting and, well, get confused.
There isn't a need for a toggle... unless to make it (slightly) more difficult to, say, turn off the "advertisements" category for certain apps?
https://addons.mozilla.org/en-US/firefox/addon/istilldontcareaboutcookies/