For a short while it was quite fashionable to have really small Windows programs around, before broadband was common enough, as a reaction to bloated programs, Java runtimes, multi-megabyte VB executables etc. Saw quite a number of assembly-based editors back then. But to be honest, most of those were a small wrapper around the Windows edit controls...
And does this webserver serve many simultaneous connections? I doubt it. You'd learn more about proper webserver programming techniques by studying the source code to nginx [1] or mongrel2 [2].
As an example, it's more useful in showing how to build GUIs in assembly, and that's not very productive. You do get small executables, tho.
[1] http://nginx.org/en/
[2] http://mongrel2.org/home