I do not buy into the IT theory, but from what I have read and watched on Youtube, it is intriguing. Do IT theorists believe it occurred at the moment Shepard was zapped by Harbinger on earth prior to his ascension to the CItadel or during his final confrontation with TIM? I ask, because if IT were to have happened following Shepard getting zapped by Harbinger's beam on earth, I assume that nothing from that point forward, including the final choices presented to Shepard would have actually been real, but in his head. If that were the case, it would seem that the Reapers would have continued the cleansing of all advanced species. Am I missing something here?
The ''indoctrination attempt'' starts when Shepard is hit by the beam.
There are a few factors that suggest this:
1. Before the laser beam, the path to the Beam had no vegetation. After Shepard wakes up, the path has vegetation just like in Shepard's dreams ( which are believed to be the effects of his long term exposure to Reapers due to the growling and the black thingies at the perifery of his vision, which you see against TIM ).
2. Archer says no one got through the beam, despite both Shepard and Anderson getting in.
3. Harbinger leaves for no good reason.
4. Anderson getting shot lowers the EMS. This is suggested by Anderson being Shepard's sanity and TIM being the strength of the Indoctrination. If Anderson ( Sanity ) dies, you need more EMS to get the ''Shepard lives'' ending.
5. The colors of the endings being reversed. Destroy is Red, Control is Blue. It's because that's what the Reapers want.
6. Shepard looking like a Husk if choosing Control or Synthesis.
and so on and so on.
As for the ending, why does it have to end? That's a clear inception ending, for IT. It's open ended. You can imagine whatever you feel like. I imagine that in High EMS destroy ( the only one in which Shepard wakes up ) he makes his way to the beam and opens the Citadel, after which a Destroy in which the AIs live plays.
EC disproving IT
If the writers were to say IT is false, I'd believe it.
But EC proves nothing, as EC was not meant to happen. EC was simply created by fan pressure and nothing else.
A desperate attempt to salvage what was left of their fan support.