Capacity planning challenges can't be ignored and it's interesting that Pinterest share their forecasts with AWS significantly in advance. Makes me wonder if AWS will offer more incentives to older/larger enterprises that are used to datacenter-era capacity planning, I suppose RIs and Savings Plans are a manifestation of that already.
For big orgs it’s quite common to have NDA’s with AWS and embed their staff for support and decision making. You get expertise and insights into the upcoming roadmap as well. It would be no surprise to know that Pinterest shared these details with AWS.