I don&#x27;t know, hence my diplomatic silence. :-)<p>I think it&#x27;s to do with predictibility: back-compatibility, discoverability. You can get new coders who can get up to speed on a codebase. Business customers - who really really want things to keep working - value that. And business customers ultimately decide what is used.  Similar to your point. BTW I&#x27;m not even sure expert lisp programmers can easily maintain their own code (or, perhaps more importantly, would want to).<p>Operator overloading: very cool, nice for matrices, complex numbers etc. But easily abused to create impenetrable code (you must first get across all the definitions). C++ had it, Java avoided it. Lisp is so flexible, it&#x27;s like everything is an overloadable operator.<p>I&#x27;m not aware of such research on lisp; but the only successful lisp projects I&#x27;ve heard of are with hot-shot coders. BTW: reddit was originaly written in lisp (inspired by pg, who gave them the idea for reddit); they switched to python.