The practice of running all daemons as "nobody" was a historical mistake. This has been
corrected in Debian and (I hope) most other Linux distributions. Each daemon runs as a
separate user, which prevents both accidental and malicious interference with other daemons.
The extreme example is qmail, which has four user accounts and no license.
I think "run as nobody" has become a shorthand for "run as an unprivileged user instead of
root", and that is how the article was using it. I think the LWN guys are clueful enough that
they wouldn't suggest we literally run the X server as the "nobody" user.