Tried putting R into production recently? It’s a frustrating and brittle experience. Don’t get me wrong, R is fantastic at what it does - analysis, research, statistics, and arguably the API’s on the R data frame packages are a lot saner than Pandas.
C++ is out for different reasons I suspect. As this touches on, “modellers” (and data scientists/engineers) ought to be decent developers, but a lot of them are not, and in my experience actively refuse to learn any of these skills, the comfort zone is “jupyter notebooks” and that’s it. Getting them to write C++ (disregarding language debates), a language that is unequivocally more difficult and fraught with complexity than Python is basically a non-starter.
Do I wish it was different? Yep. Do I wish there was some more variety in the “language ecosystem” so it’s more than just the “lowest common denominator Python” dominance? Absolutely.