I think that the lack of mention of R just points out that most applied data science oriented startups are for the large part run by computer scientists / software engineers rather than statisticians or applied mathematicians.
R is heavily fragmented and requires at least some willingness to read papers, identify the right package for the right task, and in many cases interpret non-standardized output.
Python on the other hand has 2 consolidated modules - numpy and scipy - that for most basic data science tasks are good enough and easy enough for someone not trained in statistics to understand.
