In past we had kept it there so people would notice they can track different sites with it. However, the "all websites" screen achieves the same.

Having less controls makes the UI easier, and also makes it easier when no data has been tracked yet.

We could keep it though if we add a link "Add new site" after "all websites". This link would however only appear to super users so for other users the site selector be still useless. I'd prefer to remove the site selector therefore when there is only one site.

Here's a screenshot of our demo