Because it doesn't meet academic standards for publishing in NIPS and ICML, the most prestigious machine learning conferences.
Edit: To clarify, research papers generally cite other peer-reviewed research papers in similar venues preferentially. ML papers should mostly be citing ML papers in high-quality, peer-reviewed venues. HTM doesn't have papers like this to cite.
Edit: To clarify, research papers generally cite other peer-reviewed research papers in similar venues preferentially. ML papers should mostly be citing ML papers in high-quality, peer-reviewed venues. HTM doesn't have papers like this to cite.