Most of what Chrome does unconventionally
From the point of view of this 20+ years IT guy is style-farting.
And sadly the Mozilla guys rather than producing a solid browser with no stupid bugs or with worth it functionality they decide to style-fart too.
I will reason this so everybody will understand what I mean:
Chrome as a standalone browser with no extensions whatsoever is a nifty application, and something worth of my time.
Firefox without extensions as a standalone browser is a waste of time.
Take for example its really poor download manager, its record retarded bookmark dialog (search something, give me back results, but doesn't tell me under which folder the found bookmark is) and its sad devotion to try to solve problems that bother no one like the stupid page manager to group pages which is clearly inferior (and ugly) to for example the extension showcase.
Thunderbird is the same, the same old boring email client missing functionality that has been present in outlook for 10+ years, but copying the bloody vote button functionality of outlook is not as cool as copying Chrome's stupid version system.
And let's not talk about the bugs, like the one that prevents Firefox in Linux from using the pop-up menus until you minimize-unminimize the window.
Or the pervasive Thunderbird crashes each time you close Thunderbird, etc.