Stealth has a 2 minute cooldown, son. Plus, you can pull me out of it and the stealth detection in this game is ridiculous.
Also, you have Guardian Leap, which is one of the best defensive abilities ever, for both you and the person you're using it on. You can instantly leap out harms way to one of your ranged DPS.
Has to jump in to attack? Son, Operative has to run in, we don't even have a proper gap closer. Plus our nuke requires us to be in stealth and behind the target in melee range without being pulled from stealth AND it hits for less than smash and smash is an AoE. Not to mention the fact that it's guaranteed crit, hidden strike isn't.
Sure, take my stun, if I get an AoE that allows me to crit 5 people for 6k consistantly.
You really can't compare Guardian to Operative.