No, 200% is rendering 4 pixels with "features" 2x larger in each axis. You may get 200% scaling as you said with some legacy apps that give zero fucks about dpi scaling but are still scaled trough some mechanism to properly match other apps.
Fractional scaling has been a problem across all platforms, but I agree Linux has taken its time to get it right and still have some gotchas. You should try to avoid it in any platform honestly, you can get sometimes get blurry apps even in Windows. AFAIK KDE is the first to get it right in this complex situations where you mix multiple monitors with different fractional scaling ratios and have legacy apps to boot. GNOME has had experimental fractional scaling for a while but it's still hidden behind a flag.
It also helps to not have nVidia trash on your old (and sometimes even new) computers if you want longevity. My old machines have intel and AMD graphics with full support from current kernel and mesa.
Fractional scaling has been a problem across all platforms, but I agree Linux has taken its time to get it right and still have some gotchas. You should try to avoid it in any platform honestly, you can get sometimes get blurry apps even in Windows. AFAIK KDE is the first to get it right in this complex situations where you mix multiple monitors with different fractional scaling ratios and have legacy apps to boot. GNOME has had experimental fractional scaling for a while but it's still hidden behind a flag.
It also helps to not have nVidia trash on your old (and sometimes even new) computers if you want longevity. My old machines have intel and AMD graphics with full support from current kernel and mesa.