Gmail, outlook web, whatsapp web, slack web … just some examples of webapps that I use or used in the past that someone might legitimately want notifications from. Maybe you don’t use them, or are not required to use them for work, and that’s fine.

The article is specifically talking about android though, and there you’d most likely use an app for those, so I personally never needed them on mobile, but I can see someone else might need them.