It's possible that Google simply couldn't afford them anymore. At these unicorns they are leading, their current and projected net worth is so huge that even a

It's possible that Google simply couldn't afford them anymore. At these unicorns they are leading, their current and projected net worth is so huge that even a company like Google might not be able to justify paying it without serious disruption. I always thought that's what Alphabet was for, to be honest. Trying to keep a sort of ecosystem of acquisitions and Google spin-off startups with direct Google investment.