This essay feels overall hopeful, and I really hope Firefox distinguishes itself as the go-to browser for "power users" at least (while all I run anymore is Linux, I don't consider myself a power user so much as a cheapskate with an idealistic/irrational sense of fairness who used to tinker a lot more but who now just likes things to work on decade-old hardware and thus sticks with Linux Mint). The side tabs thing is a real lack, and so far I just use the dropdown on the upper right and either scroll or search. Sometimes I double-click the side arrows on the tab bar to scroll by a window's amount of tabs. None of those options are tree-style tabs, though. I know there are ways and extensions, but this should really be baked in- horizontal text stacks well, especially on these wide screens.