Harnesses only work if the seat is there to hold you to the seat. Leave 2 inches of slack in all the harness belts, same thing.

so again, WTF is your point? the seat isn't going to slide out from under you, pull itself from behind you, and disappear. The harness holds you to it. even with 2 inches of slack its still going nowhere.

So instead of trying to sound like a smart guy, why don't you either make a valid argument or stfu.
I'm all for quality items when quality is needed. In this case I'm desperately trying to get a valid argument against knockoff seats and you're failing at providing one.

Fine, I need to remember my pro-Darwinism stance anyways.

Air bags are designed to work with 3 points belts, not 6 point harnesses. If you contact an air bag with a harness you don't have it installed or adjusted properly.
Part of the FIA testing procedure simulates a backwards impact into the guardrail (showing the seat is strong enough not to break under the weight of the occupant). If a seat breaks or bends it could cause contact with the roll bar/cage and also allows the belts to loosen... which could become a huge deal depending on what happens next (rollover, contact with another car, etc)

Funny part is there are used FIA cert seats floating out there for good prices if you look around. I paid $150 for my brand new Momo Cup VTR and $80 for a Cobra Imola II with a couple cigarette burns.

The point is that, yes, in fact, the seat may no longer be underneath you. If the seat tears loose or breaks in some fashion in the initial impact, it is no longer supporting you during the rest of the crash. If the car then rolls, sure the rollbar still does its job, but the harness cannot, because you are sliding around underneath it. To expect the harness to hold both you and an unsupported seat in place through any kind of further impact is simply unrealistic. The harness is supposed to hold you to the structure, and the structure in that equation is the seat. Putting a seat of completely unknown build quality underneath you, with homemade mounts made from mild untreated steel and random bolts from Lowe's Home Racing Dept, is playing russian roulette, even on the street.

Soviet does it with the taiwan Brides he uses, and gets away with it without getting any crap because, well, he's Soviet, and russian roulette is part of his cultural heritage.

Yes, look for the real road racers, they have to replace their seats constantly because the SCCA put a limit on how long seats are good for, or some garbage. I can understand putting an expiration date on harnesses and fire suites because UV light does break down those materials, but not seats.