Tabs have been above the address bar as default in Opera for more than 10 years, probably first than any other browsers...
It makes sense in UX and appearance because all the elements, like the URL field and navigation buttons feel like they belong to and control the active tab like in a hierarchy, and they do (the toolbars below the tab bar are highlighted in the same while color as the active tab, while the inactive tabs are darker).
A clear benefit nowadays is that tabs can merge with the title bar so there will be less wasted screen space.
What's the benefit of having them below the address field? None.