Auditors would stick to the the accounting standards and conventions to give a monetary value to users and other intangible stuff. Whereas the market (in theory) can value the whole company's ability to use these intangibles to generate money in the future. That's why there's often a significant difference between the "assets - liabilities" on the balance sheet, and the market cap. Now, whether such a big discrepancy is justified... that's another thing.

Under GAAP, there are a lot of intangibles that are not reported on the balance sheet. Basically all of facebook's internally developed intangibles are not on the BS, but all of Instagram's intangibles will be there. Kind of weird, but this is how purchase accounting works.