And they're not clever enough to deal with Safari's tab bar?
Just as humans can adapt to the tab bar shifting when tabs are opened and closed, humans can also adapt to the concept the tab bar focusing on the left or the right and collapsing the opposite side.
The point of my previous comment is you've lost literal spatial organization already, as the exact same position isn't guaranteed to be the same tab after other tabs have opened/closed, so we're already talking about dealing with relative positioning of tabs instead of absolute positioning. And Safari's tab bar does not screw with relative positioning.
It gives you less clear landmarks though. Spatial navigation through 20 items with no differentiation isn't easy. Even if you know "9 items from the right", you can't do easily do that subconsciously. "The tab next to the Stack Overflow one" or "The third Stack Overflow tab" is a lot easier in comparison. At least for me, navigating a lot of sites without favicons or large amounts with the same one decreases efficiency a lot, for exactly this reason.
Just as humans can adapt to the tab bar shifting when tabs are opened and closed, humans can also adapt to the concept the tab bar focusing on the left or the right and collapsing the opposite side.
The point of my previous comment is you've lost literal spatial organization already, as the exact same position isn't guaranteed to be the same tab after other tabs have opened/closed, so we're already talking about dealing with relative positioning of tabs instead of absolute positioning. And Safari's tab bar does not screw with relative positioning.