I was asking rhetorically, because the counterpoint is the existence of competition. Are you any less locked into a platform that has 90% market share as opposed to one that has 50%? What matters is the degree of lock in, not total market share.
By the definition of 100% market share, Microsoft wasn’t a monopoly, and they argued this in court. They argued that Netscape was on a level playing field because, like AOL, they could carpet bomb the country with install disks, while MS could include their browser on 90+% of new computers sold.
They had 94% market share in 1990's. They actually invested in Apple to keep them from going under.