If it weren't for lawyers being arbitrarily involved in things they shouldn't be, there's an excellent chance that we'd all be running BSD and Microsoft wouldn't have been nearly so dominant without BSD being legally sidelined in the early 90's, which gave Linux a very timely foothold, despite having to quickly reverse engineer a whole lot of what BSD long already had.
This effectively kept FOSS *NIX sidelined from the consumer market in the early 90s, meaning that Microsoft was left to mainly compete with other DOS based systems, which made Apple the obscure one among the many otherwise compatible offerings at HH Greg or Babbages.
Interestingly enough, when the dust settled on the lawsuit, Microsoft themselves incorporated BSD network stack code into their emerging Windows NT platform (and even offered a POSIX subsystem for it).
AT&T's own litigiousness helped make Unix obscure for the biggest emerging market for the time and instead helped Microsoft gain significant market ground on their own turf. It's not that Unix-proper is or was irrelevant, but it went from being ubiquitous to niche due to the missed or squandered opportunities, which led to the rise of Linux as the major alternative.