We can see how this works out in production, but the idea is that people signed up to immediate emails would only be picking these activities up (before the email is sent out) when they are actually in the process of doing work/collaboration in the UI. In that case, it would be annoying to receive emails for things you're actively participating in. 

It wouldn't necessarily cause people to think that the email notifications are broken. It should just strike them as expected behaviour (i.e. I get an email when something new has happened that I don't know of yet).