I find it odd that only one writeup shows an actual use for /dev/null.

Okay, so here's one. Let's say a configure script wants to probe for pthread support:

echo "#include <pthread.h>\n\nint main() { return pthread_create( NULL, NULL, NULL, NULL ); }\n" > test.c
cc test.c ${LIBS} -o test 2>/dev/null

The script makes a simple pthread program and compiles it, redirecting its error stream to /dev/null. That way the user does not see compile errors. The script then checks the return code of the C compiler. If it's zero, it compiled and there is pthread support. Otherwise, there was a compile error thus there is no support for POSIX threads, and the script can give a verbose error message.

Well, that's one usage for /dev/null.