Missing rationale behind API suffix

[azolotko]

Uber Protobuf Style Guide V2 says:

Services should always be suffixed with API. For example, TripAPI or UserAPI. This is for consistency.

"For consistency" argument is understandable, but it doesn't unfortunately explain why API suffix was chosen. This rule contradicts Google's Style Guide and it would be nice to understand why this divergence was introduced. It could've just been just "Service" suffix, right?