Except everyone is forgetting that I also mentioned Dylan, from Apple, and whose goal was to be a system programming language for the Newton OS, with the Dylan team winning over the C++ one, but internal politics made the decision to go with the outcome of the C++ team alongside NewtonScript.
I directed most of my comments towards CL because I know more about it than Dylan. My understanding is that Dylan lacks parametric types, so that comment can be straightforwardly applied to Dylan. IMO Parametric types are a really important part of this.
Regarding performance, I don't know much about this in Dylan. Was Dylan able to completely remove the runtime overhead of multiple dispatch for type stable code?
I think Dylan would be (perhaps ironically) the Newton in this analogy. (or maybe General Magic?)
Pioneering and ahead of its time in many ways, but for whatever reason it seems that the use of multiple dispatch in Dylan seems to have not (yet?) led to the same level of ecosystem-wide composability.