I'm sure there's a very similar question here somewhere but I'll give you a quick answer rather than digging around for it.
First, beware when reading Pi related blogs, tutorials, etc. online (including questions here) to check the date, because things can change over time, as they have in this case. Unfortunately, not everyone who posts information online seems to consider this relevant, as in this case -- being mediawiki based, elinux articles require you to look through the View History tab to get the date.
So this time you are mostly blameless, but that page has not been updated in almost 3 1/2 years.
/etc/inittab is a relic of SysV init, which was used by Debian (and therefore Raspbian) up until version 8 (the current one as of about a year ago -- and note there was no Raspbian 1-6, it started at 7, the numbers follow Debian, which has been around for a few decades).
The replacement for SysV init is systemd; as per bluepinto's answer the easiest way to set up autologin in any case is via
raspi-config (which has been kept up to date with changes to the init system).