"In the cases such as Google, they also tend to create a monoculture which probably feels right at the moment but I think really hurts the company in the long term"

I would agree with you about the monoculture aspect where they tend to hire new college grads from mostly the top colleges. I thought it's a little bit too inbred, but they also buy a lot of companies and get a much broader set of employees that way. Although, they might dump a lot of the acquired employees instead of keeping them on permanently once the acquisition goes through.