[hga]

Two arguments here are that:

  1. Qi/Shen are very young, less than 10 years old.
  2. Their adoption has been crippled by wonky licenses.

That said, the sequent calculus can be viewed as an implementation detail, I don't believe it's integral to the use of Shen. There are arguments for adding features from non-Lisp functional languages, which I'll note in the forms of OCaml, F# and Haskell are seeing real world use.

I'll come back to this question after learning Shen (the wonky license has kept me from more than dipping my toe into it).