They do mention him. When they talk about the mountain path and about you being strong enough with the voice to make your way up there. They think you're strong enough by the time you stop around to ask about dragonrend. How much of the main quest do you remember?
How much of the main quest do you remember? They don't mention their leader Paarthurnax until you ask about Dragonrend, Arngeir then refuses to help you further claiming your not ready to meet with their leader and it has nothing to do with strength but philosophy. Paarthurnax overrides them by shouting down the mountain. If not for Esbern making the dragonborn aware of Dragonrend the protagonists might not arrive at the throat of the world to talk with Paarthurnax until its to late to save the world.
You only know to ask about Dragonrend because of Esbern and you only know about Paarthurnax because you asked about dragonrend. Now your free to rewrite the game to edit out the importants of the blades but I could rewrite the game to edit out the importance of Paarthurnax and the Greybeards. You could learn all the words from walls and dragonsouls and then Esbern finds the records on the wall of how Alduin was thrown forward in time using an elderscroll and figures you could use the scroll at that location to travel back and learn dragonrend.
You rewrite the game to take away anyones importance to the plot, but as it was written the blades were necessary.