[pas]

Similar to the marketing/advertising axiom: 80% of all marketing spending is waste, but you you will only know after it has been spent.

[saagarjha]

What many companies seem to fail to realize is that for a significant portion of advertising you'll never know if it was a waste or not.

[nitrobeast]

I'm unfamiliar with marketing but I suspect the situation is much better now with all the tracking. And I can imagine for many APIs, people do know what most frequently used features are, and what typical users are like.