Problem
Perform a task and need to make multiple calls to various backend services. An application could rely on many services.
Solution
Use a gateway to reduce chatiness between the client and the services.
API Gateway Aggregation in Practice
API Gateway products usually act like a reverse proxy for ingress communication, where you can also filter the APIs from the internal microservices plus apply authorization to the published APIs in this single tier.
It might have a single API Gateway is not so risky because these kinds of API Gateways are "thinner", meaning that you don't implement custom C# code that could evolve towards a monolithic component.