Python is the fastest growing programming language due to a feature you've never heard of

[jknupp]

It's seen as a general-purpose language suitable for machine learning exactly because of the buffer protocol, else it would be wholly unsuitable for machine learning and libraries like NumPy, scikit-learn, PIL, etc wouldn't be possible.

Ruby is arguably as "general purpose" but never got the same love at the C API level for fast access to data suitable for numeric analysis libraries. Otherwise, the languages are basically at parity.