Comment by Quarrelsome

Firefox was over reliant on plug-ins, gave plug-ins too much power and the plug-in as well as firefox update mechanisms were messy. Chrome did more out of the box than firefox reducing the need for plug-ins, sandboxed plug-ins from destroying general browser performance and most importantly realised that updating was not a user concern and performed updates silently. There were also other innovations that Chrome did first that put them ahead of the field (I particularly remember their genius tab closing behaviour).

_That's_ why they "won" not because of fucking adverts.