Well, of course you can make such a web server on any OS where you can modify or extend the kernel, but TUX is not exactly a popular or recommended solution. There's a reason the reference manual is dated 2001.

To be honest, the original version of http.sys (XP SP2/Server 2003) dates back to the same period.

I didn't express myself correctly; the latest version of the reference manual is from 2001.

Deploying this sort of thing in production on the other hand seems to be a Windows specific idea.

IIS is marketted by MS as a VERY capable web server... typically out-performing other web servers by a large margin. The caching system for IIS has always been one of their crowning achievements, working better than most systems. Though, these days most will put a caching server(or cluster) in front of their operations servers. Just the same, it has worked pretty well. Though I predict this feature will be removed, or disabled by default in future versions.

I'm kind of surprised this issue wasn't discovered previously. Fortunately, there doesn't seem to be an exploit beyond crashing the server yet (which is bad enough). (sigh, kind of glad I'm in the process of migrating everything away from IIS).

That you can write a module to serve HTTP from kernel space is a given.

That people actually use it is another topic.