>linux was originally intended to not contain large libraries of drivers
Huh? Support for obscure hardware has always been a big selling point for linux.
>the drivers that it does have are often not as good as those on windows.
Quite the opposite IME. With windows you will always get some kind of driver, but it will usually be buggy. Linux doesn't always have drivers, but those it does have tend to be very reliable.
>If you want to use a scanner that is not supported by x-sane on linux, you have a very short list of options
Sure. But how many scanners is that? Maybe I've been lucky, but all of mine (mostly HP, who admittedly have a reputation as being especially good with linux) have "just worked".
>If you want to use certain multiple monitor setups, you typically have to install the buggy proprietary drivers.
Buggy? Maybe by linux standards, but I've found the nvidia graphics drivers far more reliable than any I've used on windows (it's a shame that ideology means installing them is poorly integrated). Admittedly the way modern windows can seamlessly restart its graphics drivers mitigates this a lot - but linux hasn't needed such a thing yet.
With Intel graphics you can do multi-monitor just fine with the open source drivers. I don't know about AMD.