In "paceline" riding, there is someone at the front of the line and the rest of the line drafts, or gets into his/her "jet stream" and allow the wind to pull them so they can take it easy and spin. It's not really "pulling" the whole group, it doesn't make it harder on the leader. Every so often, the leader moves out and to the back of the group to let someone else pull for a while, and everyone takes turns. That's when it's acceptable to draft. When someone comes up from behind, lets a group pull him/her and doesn't take his/her turn pulling without asking permission, that's when it's a "no-no".

It's just manners...........