Mockito mock(clazz, delegatesTo(..)) vs anonymous class

I'm working on GRPC client for the server. In GRPC repo the advise is to mock a service in a such manner:

     private final GreeterGrpc.GreeterImplBase serviceImpl =
      mock(GreeterGrpc.GreeterImplBase.class, delegatesTo(
          new GreeterGrpc.GreeterImplBase() {
          // By default the client will receive Status.UNIMPLEMENTED for all RPCs.
          // You might need to implement necessary behaviors for your test here, like this:
          //
          // @Override
          // public void sayHello(HelloRequest request, StreamObserver<HelloReply> respObserver) {
          //   respObserver.onNext(HelloReply.getDefaultInstance());
          //   respObserver.onCompleted();
          // }
          }));

https://github.com/grpc/grpc-java/blob/master/examples/src/test/java/io/grpc/examples/helloworld/HelloWorldClientTest.java

I wonder, what would change if I just replace

mock(GreeterGrpc.GreeterImplBase.class, delegatesTo(

with anonymous class creation like this:

 private final GreeterGrpc.GreeterImplBase serviceImpl =
          new GreeterGrpc.GreeterImplBase() {
          // By default the client will receive Status.UNIMPLEMENTED for all RPCs.
          // You might need to implement necessary behaviors for your test here, like this:
          //
          // @Override
          // public void sayHello(HelloRequest request, StreamObserver<HelloReply> respObserver) {
          //   respObserver.onNext(HelloReply.getDefaultInstance());
          //   respObserver.onCompleted();
          // }
          };

I don't see any benefits Mockito can offer here as all calls are delegated to the delegate.

Is it correct or am I missing something?