Why do MMA matches last so long ?

They have just started doing this in Plymouth and they take ages.

Surely if your hard enough / fit enough / good at fighting enough to want to do MMA, youll be good at it and able to end it ?

Im unsure of the rules but i believe no eye gouging and no groin stuff is allowed, everything else is fine ? So why dont they just neck jab each other, done correctly the fight would be over within the first 3 seconds.

I have correctly had to perform this move before on the street when threatened and it worked perfectly.