The main friction reduction, for me at least, is the consolidated billing that avoids extra bureaucracy in corporate environments. The API-translation/abstraction tends to cause more problems than it solves.

I’d prefer something that consolidates billing, but still lets me use providers' APIs directly (or via some "raw HTTP" proxy). There are plenty of unified API gateways, but I haven’t seen one that is just billing/auth in front of the native provider APIs.