Good points! The unfortunate side effect of having 4k and 8k screens is that 1080p is still common. I could understand why they'd assume nobody leaves a browser

Good points! The unfortunate side effect of having 4k and 8k screens is that 1080p is still common. I could understand why they'd assume nobody leaves a browser window covering only a quarter of their screen, but at the same time, both major browsers have a Responsive Mode where you can test screen resolutions, orientations, and tap events. There are devices with resolutions under 800x600 still accessing the Web. Every developer has to place where their own minimum threshold of consideration is. I personally aim for those old-school resolutions as the minimum, and may move upwards to something like 720p if it's a bit more complex. My screen itself is 1080p, so if it looks good at full screen, it will probably look decent on 4k as well as long as I'm using scaling units.