Originally, things worked this way – you had to track or watch things to add them to your sidebar.
We found that there were several cases where folks wanted to have easy access to things from their sidebar but did not want all the extra notifications. This caused people to either get much more notificaton noise – or – to just opt not to put things in the sidebar that they would have liked to.
So, we decided to decouple them.
I think we’re now in an in-between state in our design though.
I like not having to track things to put them in my sidebar, but I agree that it probably makes sense to put things in my sidebar if I do track them. I think it’s likely that we’ll make a change in that direction at some point.