It is not essential to hang back. What we are saying is if you want a BONUS, you might need to hang back.
I am all for player empowerment and the rule of fun, but believe some things have to be earned and choices should matter. You can still fight a group on your terms without surprise, you just don't always get a round of freebies. Freebies are EXTRA and not mandatory.
However, people gotta do what is right for their individual game.
I like the distinction some others have made and will consider it myself. Getting right up on someone should be riskier. However, as a group travelling overland, it might make sense for a group check to remain undetected a la Lord of the Rings with Strider leading the way and per the movies, Frodo yelling at friends not to have a fire at the top of a hill! THAT seemed like a group effort (and a group fail)!
I would make the distinction between whether or not others could perhaps influence the choices and actions of party members. Just myself, I do not see waldo the thief being able to help bruno the fighter be quiet up close in heavy armor.
Either way, have fun!