Politics --- literally. The CM's market niche was high-end research, and most of the sales there were to labs and projects funded by ARPA (or DARPA; the D comes and goes). This led to accusations from competitors that [D]ARPA was steering the labs to the CM, which got a sympathetic ear in Congress --- and all of a sudden, the CM was completely unacceptable to [D]ARPA.

(Accounts of this vary; as an ex-employee and friend of many who remained during this period, the technical staff certainly believed that they were winning those sales with a better product, but those at, say, Kendall Square Research almost certainly believed the opposite, in good faith.)