This is not true. It is not the only way, it is one way. And as you've suggested, can be catastrophic if you miss. The name of the game with McBean is conservative. They eilk, IMO, Sit where they are and take a QB they like while building the team up around them. And if that guy they took doesn't pan out, they will try again and the loss of the draft capital wouldn't be as devistating.
I never understand the desire to move up and spend more on a player that, to be honest, no one knows how they'll perform.