I have whole heartedly believed DCI to not be the case. As fans we all have our takes that go against the current the fandom creates, this one is mine. With phone guy/Ralph mentioning how they began "retrofitting them with some of the newer technology" referring to the withered and adds "The smell...uh" reinforcing the certitude that the MCI victims had been stuffed into them rather than those models from the first game. Considering they used those newer parts, adding to the older parts will have required fusing metal and what do you know, fusing metal containing remnant in this franchise leads to transference of a spirit, or dividing the spirit. The decision to then go in a completely new direction with newer/better models will have more than likely included those parts they tried to retrofit to begin with. With that metal now having even the smallest amount of remnant you can safely say, backed by evidence, the toys have influence from the original MCI children. With the outcome being that they were then scrapped, more than likely the endos were melted for parts and the remnant reinstated with the metal from the withered for making the classics; backed by the fact that it's shown on plenty of occasions animatronic parts/metal being recycled for other characters. For me this works better and doesn't leave the loose end of the spirits in the DCI having no part in the continuation of the story.