No it's just ignorance. PL design is just one of the few areas where academia leads industry by a wide margin in understanding how to design compilers and type

No it's just ignorance. PL design is just one of the few areas where academia leads industry by a wide margin in understanding how to design compilers and type systems. Where academia lags and why these features fail to make it into production languages is that industry needs working compilers, build systems, debuggers, package managers, and linters more than it needs any kind of static typing. The other problem is incentive and design approach. The academic approach to PL design is to carefully develop the type system and understand the way the rules interact, proving things like soundness, decidability, etc. the industry approach to software development is MVP. These two approaches are incompatible and lead to different language designs, because you can't slap a carefully designed system on top of a recklessly developed MVP that has been bumped incrementally over a long time. At least not without major time consuming rewrites.