Why not to use standart way for callbacks? about tutorial HOT 1 OPEN

It's just one way of doing it. The whole point of cell is that you can do whatever you want because it just provides the most minimal yet powerful structure you can build your app around.

That example was to show that you can even pass around cell nodes between one another, the metaphor is kinda cool.

But you can really do whatever you want. Like the documentation says, the only things you need to remember are the fundamental rules. Everything else is up to you. Hope this makes sense.

from tutorial.