It did, but those were static tabs. It was pretty easy to create tabs as a form of sub-organization. But the treatment of tabs as documents was new-ish to Chrome/Firefox. Other applications treated multiple, concurrent document views as whole, resizable, sub windows inside of an "MDI" panel.

Look at how older versions of Word, Excel, and Visual Studio worked. The tool trays stay consistant as you move between document windows. The entire application is minimizable and quittable together as one.

Photoshop still uses this metaphor. In the ealry and mid-2000s, Photoshop on Windows had a window for the application separate from the documents, but on Apple OS9 and OSX, the only representation of the application itself was in the menu bar. Document windows and tooltray windows both floated in the same desktop space as every other window.

I haven't checked on the GNU Image Manipulation Program, but I seem to remember it retained the same "no application window, tooltrays and doc windows exist in the DE" metaphor for much longer than Photoshop.

There is also a difference in the way that Chrome renders tabs in the window title area. That's a part of the UI chrome that one would expect to be in the perview of the UI toolkit, but Google took it on themselves.

Virtual desktops in Unix predate Visual Studio. I'm pretty sure there was a concept of tabbed interfaces somewhere in the Amiga or BeOS or any other OS.

https://en.wikipedia.org/wiki/Tab_(interface)

Don Hopkins himself can enlighten us about it (NeWS) better than me literally anyone in this thread, jut wait.