Yet characteristics such as high information density and very accurate mouse interaction are all thrown out of the window, because of how the admin looks like on a phone.
How is it responsive to ALL devices, when mobile first enforces such restrictions on a design.
It's fine to make it (hover effects) functional for desktop users rather than just using it for visuals, but you need to make sure that said functionality exists in another form for mobile. Otherwise, you're just giving a be "F* You!" to mobile users since the experience on your site is broken.
In practice, we often have to choose between providing a bad mobile experience, or making the desktop experience weaker, by not using many tricks that are not available in the small touchscreen environment. It's not an issue of design, but dollars and cents.
Consider Google, which says that mobile search outnumbers desktop in 10 major countries. Do you hear Larry Page moaning about how people are using the "wrong" method to access the site? Nope. Instead, Google rejigged its algorithm to favour "mobile-friendly" sites. So let's see, that ranges you, preferring desktop, against Google, monitoring the direction of travel. Think I'd bet with the latter.
You can bemoan the way that mobile input has to adapt. Or you can revel in the way that smart UX designers figure the best way to adapt, as outlined in the original post. I know which I prefer.
Every smartphone sold in America in the last four years has a far higher screen resolution than the machine on which I first browsed the internet back in the 1990s. Indeed, most of them have a higher screen resolution than the laptop on which I regularly browse the internet today!
So, no, the viewports on mobile devices aren't really smaller.
It is -however- very true that one's input method is substantially less precise than when using a mouse. But, it's not that much less precise than when using a pen or stylus. :)
> Instead, Google rejigged its algorithm to favour "mobile-friendly" sites.
Sure. But, OP is not talking about Google's search ranking algorithm. Google didn't make dumbed-down versions of the UI of their sites because folks are mostly visiting with finger-navigated devices. Until recently, Google worked hard to make UIs that are both full-featured and useful for folks navigating with a mouse and with their finger.
A good point, and important to keep in mind.
> So, no, the viewports on mobile devices aren't really smaller.
Except, in the ways that they are. A 5" 4K display is still literally a smaller viewport than a 13" 1366x768 display or a 20" 1920x1080 display, and this is quite important in design.
I would call the concept which you are calling "viewport", "screen". e.g. "This phone has a much smaller screen than this nice desktop monitor."
That is not an excuse to give up on high information density on the desktop, just because your headings have to be ridicoulessly big for mobile.