You'll be more or less forced to upgrade at some point. Chrome, Slack, and pretty much everything else stopped supporting 10.8 this year. Even CLI apps like Keybase refuse to run.
I'd also point out how frustrating it is that Linux laptops tend to be on the cheap side (on par with a 13" Air), or generally massive, plastic, and loud.
I haven't found the good combination and bought a new MBP and still happy with it.
But it's certainly not unusable. It's not a good thing, by any stretch, it's a pretty face over a horrific monstrosity, but it's usable.
But the fight between the systemd/non-systemd camps, especially in the form of docker/rkt, is a real pain for both sides.
I've used UNIX for ages, started on Sun OS (pre-Solaris), HP-UX, have used several early Linux distros, RedHat, SuSE, Debian, Mandrake (!), FreeBSD for a year or so, and now I use Ubuntu for personal stuff and Centos professionally.
I wouldn't use a Linux loaded laptop.
What OS X has?
Great hardware (Linus himself used to praise the Air for example -- which he used as a personal machine until 2014, and complained why no other company could make something like that -- he now uses a hi-end Chromebook).
No messing to get it to sleep, work with external monitors, including dual 4K, import camera photos and videos, work with new RAW formats, external peripherals etc. And by no messing I mean "an order of magnitude less messing that those things take in Linux".
Certified UNIX with full terminal access, bash, classic userland, etc.
Several package managers (brew, macports etc) to get 99% of anything one will need in Linux. And make && make install etc usually just works too, if one is so inclined.
Runs Linux on a VM just fine -- why would a developer pollute their OS with development environment stuff like installing DBs, compilers etc directly? And if you don't run it directly, then OS X is as good as Linux to host your developing VMs -- or SSH to some remote host.
A full, well thought out UI, even if it's not perfect. Even from 10.1 to 10.12, it never has the sudden "let's change everything and break everybody just because we can" turns that Gnome and KDE have had (I've used KDE but stopped with the 3 to 4 transition -- now I just run bare Linux or when I need a UI Linux whatever comes with Ubuntu).
Ability to run basic proprietary apps: Adobe Creative Suite, MS Office, etc. Lots of developers need those too, and I, for one, sure do for my sideprojects.
>These yearly updates seem to break everyone's workflow for a while.
No, it's just the vocal minority. Have used OS X since 2003, using it for programming (JS, Python, Java, Go, PHP, some C), video editing and music (various DAWs), and never had my workflow break, and I usually jump at a new OS the first day it comes out. The worst case was having to wait 1 month for Cubase 8.5 to support 10.11 -- but that's the fault of Steinberg for milking their customers, as other DAWs I have worked just fine, or had updates within the week or so.
Linux changes break just as many workflows (percentage wise) but there are so fewer (1/10 or so) Linux desktop users and even they so fragmented (different DEs, desktops, WMs, etc) that their laments are not really heard. Of course most major tech outlets hardly ever publish Linux related stuff in the first place, in contrast with Apple stuff that helps get eyeballs...
But Thunderbolt is not "proprietary" is an open standard adopted by the industry at large, including PC makers.
Also the "expensive Apple hardware (outdated $1000 monitors only" is not really apt. It's not that running dual monitors necessitates using old Cinema Displays. It's just that Cinema Display's are old, and Apple hasn't made any new monitors for a few years. But no need to buy/use Apple monitors for that -- and it would be foolish to buy them when there are 4K ones around by Dell etc. Apple even keeps a page with supported and tested third party 4K monitors.
Recently, I upgraded to a single 4K monitor and that did require some fiddling (using switchResX) but it still works nicely.