"The reason Google seemed a bad idea was that there were already lots of search engines and there didn't seem to be room for another." - Paul Graham
"It already exists" is a terrible reason not to do something
"It already exists" is a terrible reason not to do something
With CodeCombat and Codeacademy there UVP is very obvious (make learning to code a game and teach to code online resp.) and had not previously been done. With this site I don't understand what the UVP is (social programming challenges?) that hasn't been already by something like TopCoder, Sphere Online Judge, etc.
In short: Codecademy is meant for those who want to learn programming. Codewars is for existing programmers who want to get better at programming.