For quite a few pundits out there, the fact that there are so many Linux distributions is a bit troubling to them. I am not sure why this argument keeps coming up, but it goes something like this: there are X Linux distros out there, which is too many to choose from for users, and creates a strain on developer resources.
Taking the second argument first, it would seem on the surface that working on all these separate Linux distributions detracts from the advancement of Linux as a whole operating system. And that would be true, except for the fact that nearly all of Linux software is under some form of open source license, usually the GPL. To spell it out in very straightforward terms: if, for example, someone invents something really cool over in Pardus Linux, then chances are it will be picked up and eventually utilized in other Linuxes.
Anyone who takes the time to really look at this different variations of Linux, instead of writing article trolling for hits, will see that the differences are very small.