I've easily got 30-40 windows open at once. Console sessions on a dozen remote machines, several Web browsers with distractions and reference manuals, e-mail window, ticketing system, VMware GUI (only needed for Windows VMs, all the UNIX/Linux/BSD ones can be got to via SSH from a native terminal), a few Emacs "frames" (since they called text regions "windows" before the GUI term was well-known)....
What I don't have, though, is a need to see all of that at once. 2-3 desktops to keep things organized (business meta-management on 1, ticketing/bug fix on 2, build consoles on 3, and VMware on 4.)
I need at most 3-4 windows visible, and rarely all of them: the active command window, for example, I only need to see a few lines around the prompt. The window(s) with a man page open, that I need to see in its entirety. Basically, I need to see all of the windows I'm reading from, but very little of the one I'm writing to. (So focus-auto-raise, a la Mac, is a truly atrocious UI feature for the way I work.)
If all the new stuff is really this restrictive, I still have the source code for Motif and my .mwmrc file from 1993.