Thanks Tom, but that really did not answer my question on "why use them" I know they are legal to hunt with. If they do not rob performance then why do you need to turn up a gas block when using them ? I have never seen anyone, not , kill a deer because they did not have one. Or are they just the latest fad? And don't get me wrong, I have no problem with them, to each his own. I was just wondering why?
Don't mistake needing to tune the machine with loss of performance. Gas guns have several issues when changing ANY part of the system. Think of it like this.....ever hear one of those Fast and Furious Wanna B cars downshift and pop-pop-pop? That's because they changed something in a finely tuned and balanced system and didn't recalibrate. Same thing with altering a gas gun......can't change one thing in the gas system without re-balancing the operation of the machine! Bolt actions, lever guns, break actions, etc. have none of those issues. Autoloading pistols have their own issues adapting to using a can.....but it's nothing that hasn't been figured out already, cheaply, and readily available. Heck, we even suppress shotguns!
Like anything else that you put on the muzzle of a gun, it will (likely) alter the POA/POI relationship....but you re-zero the sights/scope to compensate. And/or you change the ammo. WHY you're using a suppressor defines the parameters of WHAT you do to get the performance result you're looking for.
I've got 30+ years owning suppressors, on all sorts of platforms from cheap to exclusively expensive, I have YET to legitimately see a can 'rob' performance short of poor installation, non-concentric threads causing off axis bores, or baffle strikes.
But you're right, it won't turn a hit into a miss, or a miss into a hit.
And if by 'latest fad' you mean readily available over the last 30 years, increasing exponentially in ownership over the last 20-ish, and ESPECIALLY the last 10 years as technology and mass production has made them cheaper, more robust, better engineered, and faster to produce........then yes.
As to recoil and muzzle blast, you're feeling it and hearing it, but your body takes precautions for momentary issues......but the damage IS being done. Over time, it adds up.
For those of us who shoot orders of magnitude more than 'average', suppressors are another tool to mitigating long term hearing damage. Appropriate for some, not so for others.
Also, I use my suppressors when introducing new shooters to firearms. The reduced recoil and muzzle blast often allows many folks to 'ease' into shooting with greater confidence, which often allows for an environment of better safety.