Nowadays, those notetaking app can annotate pdf, most of them price at 5 bucks. And pdf annotation app like PDF expert and iannotate price at 10 bucks, but actually most of their function can be replace by notetaking app such as noteability. So, why they are still rated high in chart or why a lot people buy them. There must be some reasons that they do better that notetaking app(which way better in annotating I think). Is it because they can open tousands pages pdf faster or what? Or actually notetaking apps can already replace them?