To a certain degree you have a valid point.
Most Linux distros. have an upgrade cycle. In the case of Ubuntu this is six months which also directly affects Linux Mint as it has Ubuntu at its foundation. Support usually lasts for eighteen months.
However here is the downside. If like myself until the release of Ubuntu 9.04 which is exceptional the release I preferred was Ubuntu 7.04 which meant I had to run a whole six months without support.
Here is an example of what I mean
Ubuntu 9.04 (Jaunty Jackalope) is more refined release than Ubuntu 8.10 (Intrepid Ibex)
Ubuntu 8.10 was rushed out after the release of Ubuntu 8.04 LTS (Hardy Heron) and by the time 8.10 had been released Ubuntu 8.04.1 LTS had already been released.
So most of the development had gone in to Ubuntu 8.04.1 It was not until the release of Ubuntu 9.04 major updates became available to Ubuntu 8.10
So this places Mint 6 as now the best release of that distro. even though it is based on Ubuntu 8.10 all this is down to the major updates.
As a footnote I don't really care for Mint 7 which is ironically based on Ubuntu 9.04
So yes it can serve to bewilder new Linux users as new is not always better for the very reasons I have outlined above. Only two Ubuntu releases have really hit the mark those being 7.04 and 9.04
Likewise the Mint release that stands out from the crowd is Mint 6 although Mint 4.0 was very good although based on Ubuntu 7.10 so no none of it does make sense.
The best way to approach it all is consider the major Linux distros. first which simplifies things a little
http://distrowatch.com/dwres.php?resource=major
The introduction to this Distrowatch page puts it in a nutshell
' The bewildering choice and the ever increasing number of Linux distributions can be confusing for those who are new to Linux. This is why this page was created. It lists 10 Linux distributions (plus an honourable mention of FreeBSD, by far the most popular of all of the BSDs), which are generally considered as most widely-used by Linux users around the world. There are no figures to back it up and there are many other distributions that might suit your particular purpose better, but as a general rule, all of these are popular and have very active forums or mailing lists where you can ask questions if you get stuck. Ubuntu, Linux Mint and PCLinuxOS are considered the easiest for new users who want to get productive in Linux as soon as possible without having to master all its complexities. On the other end of the spectrum, Slackware Linux, Gentoo Linux and FreeBSD are more advanced distributions that require plenty of learning before they can be used effectively. openSUSE, Fedora, Debian GNU/Linux and Mandriva Linux can be classified as good "middle-road" distributions. CentOS is an enterprise distribution, suitable for those who prefer stability, reliability and long-term support over cutting-edge features and software. '
I have in my answer confused the situation even more or cleared things up a little WHO KNOWS !
LUg.