Here's the real truth about John Connor, the first time around, before any robots were sent back to screw the timeline up: he singlehandedly held an assault base perimeter against a sustained, night-long attack when infiltrator terminators killed nearly everyone else on sentry duty. If not for Connor raising the alarm and holding the perimeter for hours against those insane odds, thousands of refugees might have been overrun and killed. Connor became a symbol of heroism, of courage, and of hope. His name became a rallying cry to inspire others to heroic acts, and his voice on the radio inspired fanatical loyalty and suicidal obedience.
He died about six months later.
He died when HKs plasma bombed his command post two years before Skynet even figured out time travel. Skynet didn't even know Connor had been killed. Neither did most of the Resistance- there's no way in hell Resistance Command would let that bit of news out.
Look. John Connor was a great warrior, and an inspiring commander. But he was just a man like any other soldier. He was a hero, no doubt, but let's face it, he got lucky, and Command exploited his name and embellished his story to legendary proportions because the Resistance needed to boost morale. Things were looking hopeless, and Connor was just the kind of story people could latch onto. But really, it could have been anyone.
In fact, that's the point. He could be anyone. John Connor is a name and a voice, nothing more. He's the Uncle Sam on recruiting posters. Right now, HQ has about six John Connors running around whipping the troops into shape, leading forlorn hopes into suicide missions. John Connors are dying all the time. Your average Resistance fighter doesn't know what he looks like; it's not like he's on TV. All they might have heard is that he has a scar over his eye, so when Command sends a guy over to lead them and says it's Connor, who are they to argue?
Skynet doesn't know what's hitting it; it doesn't have the creativity to think that the Resistance might have created a fictional character. It doesn't know anything about the value of symbolism or the hope Connor inspires in people. To Skynet, this John Connor bastard is everywhere, and he has to die.
Skynet is wasting its time, chasing a phantom and wasting invaluable resources on a target it believes is pivotal to the human war effort. That suits Resistance Command just fine. The longer Skynet devotes resources to killing a dead man, playing whack-a-mole with the half-dozen Connors in the present, the more unfocused it is and unprepared when the Resistance finishes its preparations to strike its final blow.
