No, it certainly is not necessary. However, if you want to know which hub makes money and which does not, this is one of the two ways to learn this.
At the time I was setting this up there was only one way - adsense channels, as you rightly figured out. Yes, those are url channels. You just copy your hub's url and post it into corresponding field in url channel setup under Adsense Setup->Channels->URL channels->Add new URL channel.
Nowadays you can just link your google analytics account with your adsense account, and have this information under google analytics.
Good luck. :)