Why, when one tries, the answer must always be another implementation with 'more' features instead of creating the cleanest possible implementation with 'the le

Why, when one tries, the answer must always be another implementation with 'more' features instead of creating the cleanest possible implementation with 'the least' features allowing maximum compatibility? This was said in 'The Next Lisp' http://www.lambdassociates.org/blog/nextlisp(1).htm http://www.lambdassociates.org/blog/nextlisp(1).htm