They have 98% market share in europe. They also provide the main revenue source (AdWords) and the most important implementation of the web stack (Chrome) - which fitted with mandatory automated updating. If you combine those factors, they are in a position where they can to a large part dictate what the de-facto standards for a successful website are. They can also rapidly change those standards or choose to promote or bury certain technologies.
If that is not an advantage over competitors, I don't know what is.
And this is just for the web. On Android - about half the worldwide market for mobile apps - they are not even a market participant at all. They are basically the government.