[kunj2aan]

I can speak to why there are alot of implementations of Lisp and Scheme.

Scheme seems fragmented because a lot of research work use it as the primary tool. For example, you have languages like Larceny which were primarily designed to study Garbage collections or even probabilistic language models using Church Scheme.

The ease in which Lisp and Scheme allows you to create new languages and perform exploratory work has spawned a lot of newer implementations.

And People also come up with newer implementations for a specific goal in mind. For example, Bigloo Scheme was created in order to enable Scheme programming style where C(++) is usually required.

[Someone]

I would phrase that differently: for many of their early 'users', Lisp was the object of study, not their tool. If your main question is not "I want this functionality, ASAP", but "how would I improve this tool?", it is normal to build a new, improved tool, rather than some app or library.

Ruby, perl, python, C, etc are tools for most people. People who do use them as study object will improve them by inventing a new language, rather than by tweaking them and still calling them by their original name. The main reason for that, I think, is that it is about as easy to implement a new language as it is to tweak those languages.