If UI elements are snapped to the pixel grid, then the rendered result is simply wrong. "Pixel-perfect" is an oxymoron if the logical pixels and physicals pixels don't overlap precisely. But again, Windows has the tradition to render it's UI wrong in order to achieve "sharpness", even if it looks awful.
This is true for text rendering (where Windows traditionally favors rendering to the grid, and macOS traditionally favors rendering accurately), but I think it misses the larger point that Apple ultimately has no solution, when Microsoft has a flawed one.
Here's a window at 100%, 125%, and 175%, respectively. The screen resolution remains the same; the display just uses its native resolution.
There are some flaws (which is embarrassing; how many more years does Microsoft need to get this right?) — the system icon in the top right doesn't seem to scale correctly, for example. But the entire window layout does get scaled.
Apple briefly experimented with this, but it was buggy enough that they eventually dropped the idea altogether in favor of only allowing 1x, 2x, and 3x.
If I buy a $300 24-inch 4K display, I can simply set it to 150% and have a workable solution. On macOS, I can't — I could set, say, "looks like 1440p" and have macOS downsample from that, and maybe it'll look fine, but it won't be as sharp as the above.