It is particularly bizarre to me that the tab bar is horizontal on browsers. We switched to wide screen monitors close to 20 years ago, then stubbornly continued to waste vertical real estate for UI elements. Then webpages all went hard on mobile oriented designs and literally throw away the extra horizontal space by forcing portrait layouts. Yet we still use horizontal bars that make it hard to display tab titles and can't show more than a handful of tabs without a scrollbar showing up.
I do a decent amount of front-end work, so I'll have a browser and code editor side-by side on a 29in monitor. In this situation, I very much prefer horizontal tabs. So that's one use case.
Exactly this. Plus, I rarely have over 20 tabs and even when I'm close to that number I mainly use the 10 first ones. Vertical tabs is a cool feature but both modes are useful depending your needs.
I guess it's just habit for me. I like having navigation on top, content in the middle, and OS operations on the bottom. The space was never much of a concern because
1. vertical content is scrollable anyway. if I lose a little space it's 1% more scrolling
2. if I do need the real estate it's one hotkey away. That's how Tree Tabs works, anyway. Use F1 to bring up the hierarchy and then hide it when unnedded
