One of the advantages of focusing on focus is the ability to go "deep" instead of "wide" on what a company's actual business is.
A fantastic example is Dropbox. They do one thing, and they do it with such an intense focus that I continue to be amazed by the level of innovation they achieve.
It seems like every day, their entire team is asking itself "what can we do to go deeper on our main objective?" And their main objective is to acquire as many users as possible, and then get them to store as much of their content on Dropbox as possible. Simple.
They do this so incredibly well, and their valuation is north of $4 billion, just for doing that one thing better than anyone else on the planet, with an incredible depth of focus.