"At the time, Microsoft's hegemony over the web browser market was at its peak. Firefox was the only real competitor."

Actually at the time this is referencing Firefox didn't exist (Gecko did, but Firefox didn't). I'm well aware of the history and why browsers trick out their user agents. If you want to go one level deeper, look no further than the fact that IE still pretends to be Mozilla because of the early days when they were late to the party.