The culture problem is that the team believes a tool to help get work done is to be used for frivolous activities. No amount of technological solutioning is going to prevent people from mixing "donuts in the break room" in with important "the server crashed" messages.

The culture of blaming technological problems on culture, of course.

So culturally most teams value communication, therefore you need notifications because communication is an inherently valuable good. But this is a tool for a business sector where the $$$ are generated by people in deep flow, and notifications disrupt flow. So there is a technological design failure of including a notification system but culturally not being allowed to say no to it.

For example, everyone hates the (non slack) IM system where I work because its a disruptive annoyance of little value, so we all complain much like op about the users using it wrong, when whats really wrong is the design and we don't have the strength to overrule the cultural value.