Yes, because then the library developer can define all of the things that COULD be interesting, and leave it to the user of the library to decide WHAT to record (filters), and WHERE to record it (exporters).

And since this is a standard, it means that when a user includes a bunch of disparate libraries/remote calls in his app, he can define his instrumentation wishes once for everything during app initialization. The libraries can even cooperate since they use the same underlying API and concepts for instrumentation.