the ideological underpinnings are what allowed Linux to overtake BSD during "the troubles" of the early 90s
As I understood it, also to a degree witnessing it as it happened, this lawsuit spiked BSD at the critical period: https://en.wikipedia.org/wiki/UNIX_System_Laboratories,_Inc.....
It certainly took Linux a long time to get in the ballpark of quality that BSD started out with at the gate, including the standard TCP/IP stack most everyone used, including Microsoft (initially, at least).
Oops, HN cuts the canonical URL's last character, a period; try this: https://en.wikipedia.org/wiki/USL_v._BSDI
That's pretty much the history of the FSF and the GNU projects considering they were created for political/ideological reasons (the Unix in "GNU's Not Unix" is nonfree/encumbered AT&T UNIX, and the ideological underpinnings are what allowed Linux to overtake BSD during "the troubles" of the early 90s). The pulls ideological and technical pulls have oft conflicted.