Fair point. I suspect that the one area where significant differences can be seen between those and Python is in the communities and the types of libraries available. For example, I use Pandas most days, and I'm not aware of an equivalent/replacement in Ruby or JS. Also, I would suspect (not substantiated with evidence) that companies whose products are built around data science/wrangling/statistics may be more likely to benefit from experienced Python talent in those areas than they would from another language.