It's less the distros, more the applications themselves that really fail the test. I use ubuntu on a Razer Blade 2016 and it's great but a few apps are horrible scales (due to lack of HiDPI iconography etc.)
Even windows has issues here and there with scaling. Apple really has the best tech here. That said, I switched from a rMBP to the Blade, wasn't excited about the new Macbook Pro's at all. It's a shame too, i've had 10 Macbook Pro's over the past few years, doubt i'm going back now unless the price really drops.
I just got a new hidpi linux laptop. It indeed works good enough on its own, but when I plug monitors in of varying resolutions it is pretty atrocious.
My current work setup is currently 2 1080p monitors, so to work around the weird scaling I just set the laptop display to 1080p when I am docked.
Point being, might as well just buy a laptop with equal or lower resolution to your external monitor(s).
You mean like Lenovo, or Dell, or Razer, or any one of about 10 manufacturers who have been producing quality developer laptops for the past few years (or longer, in Lenovo's case)?
Everyone else _has_ caught up with Apple. Windows 10 is actually pretty good, and Linux works great on most laptops now. There's plenty of options for developers.
I'm picking up an XPS 15 after the next refresh in January since it seems that it'll come with Kaby Lake H CPUs and (probably) an Nvidia GTX 1050.
While I have this same feeling, I think we (jointly) suffer for everyone wanting different things. I'd like a smaller (13" ish) size laptop with a handful of ports (e.g. 2x USB-A, 1x NIC, 1x external display port of _some type_ - that's it) but that's not everybody's "thing". I am definitely of the opinion, though, of having a functional thing over the "latest and greatest" (looking at you USB-C).
Unless you're talking about the color reproduction which I can't really comment on. Not really important for devs though.