Certainly the diversity of Linux distributions does serve a purpose and each particular distribution does take part in testing out what simply works best for the Linux movement enthusiasts, as well as how far certain configurations can be taken, while still maintaining usability.
EDIT:
For the question of "why", simply because one chooses to, such as one chooses to go Linux over other systems, at least assuming of majority population on this forum.
EDIT:
For the question of "why", simply because one chooses to, such as one chooses to go Linux over other systems, at least assuming of majority population on this forum.