The ecosystem of Java, .NET and the Web, and contrary to other guest programming language communities, they embrace their host platform instead of downplaying it, and talking about replacing it.

As such you get all the nice stuff that has made Lisp a great language, plus access to modern libraries.

Note that since Common Lisp there has not been another standard, and in what concerns Scheme, Dr Raket is more relevant. Also R7rs Large has been hanging on for years now.