There are not too many Linux distros. This meme needs to die. There are exactly the amount of Linux distros "the community" has found necessary to create. Sure, some die off, and new ones are born all the time. Some are vanity projects, some are single purpose. So what? Even a One Guy In A Basement Linux v1.0 is probably a worthwhile project for that One Guy - at least as a learning experience. Who are you or anybody else to tell that One Guy how she should spend her time?
I've never used Mand* distros myself, and I'm amazed that they are still going after all these twists and turns. Sounds like a viable community.
Linux community is not a centrally planned economy, or even a scarcity based economy. There is nobody who can say that the world will not have any more solutions in one space - that's a good thing.