Website admins pointed IE users to Firefox because it worked better, supported APIs and features which made their site better.
Chrome was the same too. Yes Google does have unfair advantage because they own lot of properties people interact with every day, they are a significant player for user mind space, but they are not so large that people spend 50-60% time on google products only .
I don't agree. Google is many times bigger than Mozilla. I am not talking about tech people here. Everyone uses search, youtube and android is huge outside usa. Chrome comes preinstalled in major plateforms. Even if it's not going to a google site tells them to install it. These people don't even know they can install firefox.