Being Turing complete or not is an intrinsic quality of the type system which has not been shown to have any effect whatsoever on the effectiveness of a language. Similarly, being more or less expressive, being sound or not, supporting subtyping or not, are intrinsic qualities that have not been shown to have either a positive or a negative effect. Those are all true properties -- like Coke cans being red -- but they cannot be assigned good/bad judgment other than in people's personal preferences -- until, that is, someone actually starts collecting data.
> And the "FUD" is nothing more than the very real reality that many teams find those language far too clever for their taste.
I've heard people literally say "we shouldn't use Scala because its type system is Turing complete" (in an organization that was already using Java). I call that FUD.
I agree, but we still don't know which side has the advantage and how big the effect is. I believe that if we somehow control for all other factors, the effect of linguistic features is very small, but that "simpler" languages like Java/Kotlin would have the (small) advantage over "complex" ones like Scala. I can support this from personal experience (and also for theoretical reasons), but I can't prove that. You likely have a different experience (and other theoretical justifications), but can't prove your conjecture, either.
> I call that FUD.
I call that silly. It's just as silly as using intrinsic features as a positive. We shouldn't use Scala for a hundred reasons, none of them having to do anything with the formal language acceptable by its type system. ;)
Beware of the Turing tar-pit in which everything is possible but nothing of interest is easy.
Alan Perlis