If Google found that they could make more money selling socks door-to-door than they do with YouTube, they’d have a legal requirement to do so.

This is not correct. There is a such a thing as being “on mission”. Otherwise every single company would be forced by law to turn into an investment bank which has the highest profit margins. There is no world in which a software company is forced to start selling socks to uphold a legal obligation to the shareholders.