When most people think about observability, they usually think about the visibility into the application layer. While this is arguably the most critical component, since it’s what your users actually see and judge you on, there are many other components involved in fulfilling a user’s transaction (e.g. load balancers, transaction gateways, etc.).
In the current world of distributed tracing, the focus has primarily been on providing an end-to-end view of the application tiers since it’s very difficult to “instrument” something like a load balancer. One of the goals of OpenTelemetry is to make observability a built-in platform feature. This means it’s entirely possible that cloud vendors will implement OpenTelemetry into their cloud services which provide users with the ability to observe both their application layer and external services in one end to end view.