Its 'proven' they belong together insofar a user doesnt need todo features outside jotting them down and ticking them of. Google Keep is 'awesome' if this is your mileage and you just need hierarchical lists. Keep / Notes / List / Item
A lot of to do apps handle items at an atomic level, each capable of assigning users, progress, topic-labels and even note-attachements. Thats why Whitewall says "cant imagine how many opinions there would be over real todo features" I guess.
So I think "notes with tasks" is something completely different from "tasks with notes".