It absolutely does. I have friends running the latest Windows who still report speedups after reinstalling. Who knows what sort of cruft silently accumulates in a Windows system?
> you don't need to reboot all the time
You absolutely do. Not only do users still have to reboot, Windows has become ridiculously aggressive about rebooting and updating. It doesn't matter what users are doing, it will stop everything and spend an hour applying updates, rendering the computer useless because obviously people have nothing better to do than watch the computer reboot itself continuously while a progress percentage slowly increases on the screen.