I think this article hits the nail on the head with the statement "built by statisticians, for statisticians". As a statistics student, I have found the majority of proponents of Python or Julia, as R replacements, are developers who complain either about R's speed or problems such as type checking when deploying R applications. On the other hand, most statisticians I have spoke with seem to prefer R to anything else - CRAN has a lot to do with that I think.