This was a doc handed to incoming Google engineers (along with Jeff's resume) to help assimilate them. MOst if not all of these came up at some point in the development of google.com and making decisions about (for example) whether to send an intercontinental RPC or look something up locally, or to put some part of the web index in RAM/disk.

Don't read it as "you should have known this", read it as "you should know this" to be a more effective programmer. These sorts of guidelines have been invaluable for making arch decisions throughout my career.