With the exception of some Terran comps, you can focus the detectors and then have at it with your stealthed/burrowed units.
But, for the most part, stealth and burrowing seem to be a means to an end - not a means to avoid detection. Vorazun grants the extra damage and cheat death when it’s applied, some units (Swann’s Wraiths spring to mind) get access to specific buffs, Lurkers et-al actually get to attack, Stukov’s Banshees get hyper-regen, and so on. It’s just another aura which happens to have some history.
If that’s sufficient is debatable, given it kinda ignores the original purpose of the skill.