[anonymousab]

Does it work too poorly on its own, or too poorly compared to tracking ads? Perhaps their value will go up with less presence of the latter.

[pm90]

The issue is not effectiveness as much as measurement. Advertisers value the insight obtained by tracking user response to ads. That is something they are willing to pay premium for. Without the ability to do measurements, Facebook does not provide as much value.

[ric2b]

Ad with id X was shown, Ad with id X was clicked, Ad with id X led to a purchase. Is it that important to know more than that?