Chrome is quite clearly targeted at the regular user, rather than the power user or developer/tinkerer. News flash: the regular user does not open 270 tabs, or even 10 tabs. You can tell me this claim is anecdotal, but since you have provided no evidence to substantiate your claims, I'd say the burden of proof falls on you first.
> "Firefox is better at every single thing"
Ouch. I mean, your post is littered with unsubstantiated claims, but that has to be the biggest and least substantiated of them. For starters, I think Chrome is a good deal further down the line in terms of ES6/ES7 and WebGl. Chrome is certainly ahead in the implementation of Web Platform features like Web Components and a large number of CSS properties.
I see a lot of websites which advise non-Chrome users to switch to Chrome to view the website in question -- which is horrible, but one could hardly say Firefox is therefore better at WebGl, for example.
I've also used Firefox/Firefox Web Developer Edition/Firefox Nightly many times of the years and I have generally preferred Chrome's dev tools. The ability to simulate slow network connections and to drag and reorder DOM nodes is nice in Chrome, and in general I find the dev tools to be more reliable when I'm messing with CSS properties.
The reality is that I have to use both browsers in my line of work anyway, but just wanted to say that. Obviously your retort will be that Firebug is the best, but that's kind of my point: I do not think you can say of Firefox that it is better at 'every single thing' if it must first be augmented by add-ons. Firebug will be discontinued eventually anyway when multi-process lands in stable Firefox.
So, I wouldn't say Firefox is better at every single thing. Maybe Firefox with a dozen add-ons is better than Chrome at some things, but that's the point. Regular users, and even busy developers/tinkerers, do not want to waste time configuring and setting up their browser. They just want something that will work. Chrome works better out of the box for the regular user.
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Regarding Chrome's UI, I think it caught on for a reason: just like websites have become flat and streamlined, the browser has also become more minimal in its UI, and Chrome very much led the charge there. Of course, Firefox is to be applauded for allowing the user to pick and choose which bits of the UI are visible and which are in the menu -- that's a great feature, I wish I could configure/style Chrome.
But before Chrome, this option did not exist (unless there was an add-on, it's been so long I forget), and the FF user interface had a dozen buttons, two text fields (address & search), a bottom status bar and so on. It was too much clutter. Chrome streamlined the browser UI and put things in a more logical order: tabs, then search/address, then web content. It was and is well-designed from a UI/looks perspective for the regular user.
Clearly, you are a power user and possibly a developer, so you will perhaps be more prone to having hundreds of tabs open and more inclined to spend time making everything about your browser just so. I can appreciate that. I've poured hours into browsers, tiling window managers, etc. I just don't think I'd advocate dwm/xmonad/awesome-wm to a regular user, and neither would I say a window manager represents a superior product to a desktop environment. A product isn't superior if you have to assemble/mod it yourself. This is a cornerstone of Apple's success, and VLC Media Player's success, and Google Search's success, and so on: to provide something that just works, rather than something which needs to be modded.
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No one can deny that Google has far greater reach and clout when pushing its browser down people's throats, but many developers prefer Chrome now, and not just 'rockstars', but older developers too. I do not believe they are 'casuals', I think they genuinely prefer the way Chrome works, and I think its market share is not testament only to Google's marketing power, but also to the fact that it is a successful and effective web browser.
Google Search maintains dominance today in search because of its marketing and its huge lead in terms of data, but it only reached its current level because it ultimately worked better than its competitor products. I think the same is true of Chrome -- when it started out, it represented a fast and sleek new browser product, and while it has gotten overweight as time has progressed, it still beats the competition out of the box.
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PS: I am not a Chrome salesman. I have many complaints about the product, (especially on mobile, where I think it is spectacularly weak, but that's another story). I just found your claims a little too rash. Even 'polemic' isn't adequate to describe it.