The reasoning behind mobile-first was exactly what you say is "easy" and I disagree - it is not always "easy" to shrink contents of complex desktop layouts into

The reasoning behind mobile-first was exactly what you say is "easy" and I disagree - it is not always "easy" to shrink contents of complex desktop layouts into a mobile one. Mobile first helps figure out the simplest possible version of a design. And whether building mobile first or desktop first isn't really a design choice, that's a development choice, and either way of building a site (as long IMO as you don't mix/match) is equally valid) and the same goal can be accomplished from a technical perspective. I agree though, that doesn't mean we need dumbed down desktop layouts or scaled up mobile versions, it just means we need to consider both and design accordingly. Mobile first is fine as the starting point, there are a lot of valid points to that design paradigm. But that is just the "first" part, then there are the rest of the parts to account for all viewport sizes.