I doubt your doubt :-) Resisting peer pressure is easy if it's not actually peer pressure -- if you can detach yourself and basically go "oh, I'm cooler/better than that". But resisting pressure from you true peers -- people you respect, people whose opinion you respect, people who you want to like you -- that is hard.

Same thing for defying authority. It's not a big deal to defy some assistant dean on college campus who's trying to enforce some obviously stupid rule. But not many people have the internal grit to stand up to real cops (who have zero problems with putting you in handcuffs and booking you on a variety of charges), real security services, people with real authority who actually have the power to screw up your life pretty badly.

No, peer pressure and authority are not inherently bad. But I would argue that the -- rare! -- ability to resist them when needed is a valuable feature of one's character. Knowing this ability exists is the first step.