Google culture is hiring the smartest or most motivated college grads, paying them to babysit legacy money printing systems built by the generation before them, then occasionally encouraging them to team up and clone popular services from other companies and startups.
The clones get passed around the campus for dogfooding until enough interest builds up and the project goes up the chain of command until a VP (at the time Marissa) signs off on it with notes on what to improve along with granting the necessary resources to spin it up.
Then if someone decides the project has legs they figure out how to engineer it for Google’s audience and launch. If it doesn’t work then the team disperse and move on to another project. Or it works and the team gets a moment in the sun.
Every single popular thing on the internet has a Google clone somewhere in the intranet.