This question already has an answer here:
I am a programmer, and know many programming languages, as everyone here does. Those languages have a productive purpose, a real-world application.
Python and Ruby have a clean syntax and are good for web server applications and simple infrastructure and maintenance scripts. There are many applications built with those languages for many unix distr0s (in particular with Python).
vb.net, C#, C/C++, Java and Delphi are suitable when you need native or high-performance-but-not-native development.
Other languages are better suitable for special processing (R, Matlab).
So those languages have a purpose, a goal. And I thought the spirit of the site was to use such languages to make a smallest-as-possible program satisfying the problem.
So assume I invent a language (and make the interpreter available) and use it all for my future challenges (this means: I don't invent the language for an already existing challenge). Then a new challenge comes:
Write a program that takes as input a graph as a list of integers being the nodes, and a list of integers that takes a list of connections, and resolves finding a hamiltonian loop in the graph.
Then I write my aswsome script in my awesome language (without still finding it being in P):
MyStrangeLang, 2 bytes
Wow! And I... won.
What's the fun about winning that way? Perhaps I didn't understand the site's spirit since this is my first time (these days) of being active in this site, but a good explanation would help.