> While we were building the model we also wanted to figure out what to do for these Pinners once we could target them. We thought it would be best to ask them, as they surely would know why they were using Pinterest less. So we did an in-product survey for a sample set, and found the most common reason for not using Pinterest was that they got busy.

They did mention contacting users and, as is usual, got only the symptom, not the underlying cause. Talking to users is great to understand why something happens is great, but it has to be translated through deep product insight to be useful.