Why does a click on the favorites bar open as a half page in the left sidebar

When i click on a favorite on the favorites toolbar it opens a sidebar page to the left of the page I'm on. I thought it would open in a new tab. I don't see a purpose in a half-page web page on a left sidebar.

I've found I can open the favorite bar tab and go to the website with a right click and click on open new tab, but this seems a clumsy way of getting to another website.