Replace 'Google' with 'Microsoft' in the below and it's also true, but since decades ago:

"When you have 90%+ of the market, there are no new customers to sign up. Hypothetically, they could grow by going into new lines of business, but Google is incapable of making a successful product in-house and also kills most of the products it buys from other, more innovative companies."

Key difference is, Microsoft has a long-entrenched OS monopoly; a very different animal than a monopoly on 'search' or 'advertising' online.