Monopoly power/market power don't necessarily refer only to domination of an industry, that's just the common case; network effects fall under this category eve

Monopoly power/market power don't necessarily refer only to domination of an industry, that's just the common case; network effects fall under this category even (and especially) if your company created the lock-in. Given that anti-monopoly law is being ignored these day it's unlikely you'll see enforcement extended so far, but it certainly could be. Back in the day local phone and power monopolies were very common (a close equivalent) and weren't allowed to escape regulation just 'cause their market power was local.