The sequence of events when SRS activates is:
-Massive deceleration experienced due to a sudden stop, measured by the decelerometer.
-This activates the pyrotechnic in the seatbelt retractor, which rewinds (pretensions) the inertia reel seatbelt a couple of turns.
-This stops you hitting the rapidly expanding airbag, which will probably break your neck if the pre-tensioner system didn't activate.
Which part of this is HARD to understand my bro? The whole system is pointless if there are no pre-tensioners and seat belts aren't involved because if you survive the crash, the air bag will eventually kill you.
Just go to a Honda workshop and ask them about the contents of the SRS. Go to toyota and ask them the same. Ask pros like Xulfikar. Go to a BMW/Mercedes Benz 3S shop and ask them.
Mind showing me the data that made you change your views?