VGA can barely do 2K not 4K, so most 2K and all 4K computer monitors don't include it. So it's not exactly that VGA is 'everywhere', rather that 4K computer monitors are a small section of the market, enthusiasts aside. 4K TVs are much more common - but many of those still have a VGA port (I guess TV owners are much more forgiving?).
You have 4K equipment with a VGA port. But does it actually do 4K when using VGA or does it just downscale? I haven't ever seen any VGA cable which can go above 2048×1536, and that's also the maximum wiki mentions:
When I set my mom up, in 2003 or so, I gave her one of mine 21" Integraph monitors. I was a bit jealous when I realized her computer was able to do accelerated 24 bpp 2048×1536 on that gorgeous (and back-breaking) screen. My laptop at the time could drive on external screen at 1024x768 and that was it. :-(
Ah, so it 'pays' with a low refresh rate. That makes sense.
That said, my point was that 4K computer monitors are rare (despite some communities of enthusiasts), and nearly everything currently in use has a VGA port.
VGA is an analog signal, so there is no theoretical limit, and the degradation is graceful --- edges of individual pixels will start looking blurry as you get closer to the physical limitations, but a recognisable image continues to appear.
