For 16:9 (ish) displays you have more pixels left to right than up and down, it makes sense to use up your horizontal space first when placing permanent UI elements on your screen. Still up to preference though.
Especially with the gigantic tab buttons the browser uses by default even in “compact” mode.
To think that I have lived years without knowing about those little features like combining title and menu bar to save space
The real crime here is the death of full screen monitors. Full screen just works so well for Internet browsing and programming. The switch to widescreen became common because games and movies were becoming more widescreen and that caused them to look smaller on full screen monitors. These days, the problem can be solved by getting extra large full screen monitors. Back then, that was not financially feasible.
