[shoo]

anecdotally, this interview with Shippo's CEO Laura Behrens Wu offers one idea:

https://www.joincolossus.com/episodes/74462352/behrens-when-...

Their original business idea was to build a usable API wrapping existing APIs for shipping, and sell it to mid-large ecommerce merchants. But they didn't have any existing customers and none of these larger customers wanted to buy their service as they didn't have proof of being able to handle volume. Instead they decided to target a different market niche, tiny ecommerce businesses -- but the problem with those customers is that they have no idea how to use an API, so Shippo had to build a shipping UI on top of their original API offering, and they'd sell the UI to tiny customers, until they built up enough volume and credibility to start winning some API sales to the original market segment they wanted to sell to.