My fist Linux was from 2003-4, Debian Woody. Why I learned was until 2007-8 mainly the bunch of tools from Debconf (the installer, update-alternatives, apt, dpkg-reconfigure, make-kpkg (to compile a newer kernel), debhelper and so on), not the Unix way to do things. In 2006-2009 I knew how to compile Mplayer from source (tgz) and a bunch of other tools (Cedega from CVS) with apt-get build-dep to fetch the deps and a bit more, that's it.
From 2009-2010, I've got a brief match with Slackware and Arch, and from that, OpenBSD. OpenBSD was dumb simple in design, seriously. With Linux you had to do voodoo with Artsd/ESD disabling them and then more fuckery with UCM files and DMIX. OSS under BSD's (I liked FreesBIE, a lovely live CD with FreeBSD and XFCE) just worked. And it ran faster than Linux.
Also, the Bash guides from the Howto's were utterly difficult, much more than the Ksh ones from Orelly (learning Perl for scripting was far easier, trust me).
The same way as in freebsd "service blabla start" it's a compatibility hook.
Fedora (and its derivatives like RHEL/CentOS/etc) still has the "service" command, it forwards to the corresponding systemctl command. The same for Debian (the comments in Debian's "service" command even mention it's a modified version of the RHEL/Fedora one).