I think you had it right the first time, and changing it detracted from
your real point, "Why now?"
You intentional blurred the normally clear distinction between something
sold (product/service), and a buyer. In the case of Google, Facebook,
LinkedIn, Twitter, and similar, the users of the service are the product
being sold, and the buyers are (typically) advertisers. The users are
given something useful and beneficial (search results, creepily stalking
other people, pointless "business" connections, publicly broadcasting
the precise color of your last bowl movement, etc.) to attract them, but
there must be someone else, a buyer/customer, willing to pay for it
all or you don't have a business.
In the above sense, collecting users by offering free services is really no different than manufacturing physical products; in both cases your expending capital to create a "product" with the intent of selling it for more than what it cost you to create.