Yes that's the case Christian was making (implicitly). Another case could be that (1) maybe there isn't only one right way to implement such a feature, and (2)

Yes that's the case Christian was making (implicitly). Another case could be that (1) maybe there isn't only one right way to implement such a feature, and (2) pulling the implementation down into the component layer leaves no space for experimentation or choice between different potential implementations, and (3) given the enormous pain of making any modifications in the GTK component layer (as this issue clearly demonstrates) I can sympathize with a dev that uses the component in their app shying away from the prospect of running every single idea through such a painful interaction every time they want to experiment with something. One might argue that there's a better api somewhere between "exposing raw block selection functions" and "fully-baked selection feature" that covers most needs and still provides desired flexibility, but (4) you don't find such an ideal api by theorizing from first principles, you have to derive it from experience and nobody can get such experience unless the lower-level api is available in the first place.