Well that is a user setting, and I tend to think the first retina iPhone is what started the trend.
Also, at certain screen sizes, 1:1 scaling is just impractical due to limitations of the human eye.
My 27" 4K screen is pretty much at my personal limit in terms of what I can handle at 1:1 scaling for my normal viewing distance. Had I gotten a 24" 4K screen, I'd have to set the text scaling to ~125% which would also translate into some lost screen real estate.
Scaling isn't even relevant. It makes sense to talk about scaling pixel artifacts, but not vectors one. The font is 8pt or 20pt, you can configure that on your own. 1:1 scaling is just some arbitrary and artificial fixed pixel/letter seen.
A 24" 4K screen (basically a 24" imac) had text the same size as a pre-retina 24" imac, they just used more pixels to render that text.
In any case, Windows is just using a scaling feature. But when you scale, you are losing workspace in exchange for sharpness.
When 4 physical pixels translates to 1 logical pixel, you've actually lost 3 pixels of potential real estate on a screen size where your eyes can actually discern those pixels.
On a 15" 4K monitor, losing that real estate is not a big deal, because >90% of people can't easily read or see anything scaled at 1:1 on a screen that size. When you scale that screen at 200%, you're basically using a 1080p screen with sharper text. You don't gain any real estate at all from the higher resolution.
On a 40" 4K screen, it's a whole other story. The text may not be sharp, but you can have way more windows open on that screen, which makes it easier to multitask. It's like having a grid of 2x2 20" 1080p screens.
-addendum - my visual limit is 1080p @ 1:1 on a ~14" screen, which is why I am fine with no scaling on my 4K 27" screens.