People are reasonably expected to learn k8s or React on the job, and those have a learning curve as well. Are MPI/OpenMPI much more difficult than those? I suppose that's a hard comparison to make. At first glance it doesn't look too crazy to me.

https://www.eecis.udel.edu/~youse/openmpi/#/7

MPI is trivial to learn. CS students here are expected to use it for typical scientific tasks within a few hours of lessons. Complex use cases take some time to understand backgrounds (e.g. multi partition configurations, profiling, infiniband, ...) and it's possible to become a specialist, but that's very rarely needed.

But MPI, in most use cases, comprises far less than React does, so it's not a fair comparison.

I assume all this specialized tooling will be a hurdle in the learning process. It's not like you can spin up a docker image and hack on.

I haven't used it, but shifter looks like an MLI on docker toolset.

https://docs.nersc.gov/development/shifter/examples/

Perhaps in the future, learning how to run native binaries on bare metal, will be viewed as learning specialized tooling.