I don't deny they could come together early "in a ton of different timelines". The question is: Could they come together in the actual timeline that branched off from the prime universe, given the disruption cased by Nero? Remember, this would be the same likelihood that would occur in a traditional time travel story if the prime timeline itself had be effected in the same way. So we are not talking about an infinite number of timelines to choose from.
In real life, if such things as time travel were possible? Probably not. But in Star Trek's world, yes. We've already had one similar example in Next Gen's "Yesterday's Enterprise", where an event altered 22 years in the past led to a present where everyone but Worf was where they "should" be on the USS Enterprise, despite the enourmous difference of a war with the Klingons (that the Federation was losing) raging on for most of that time. That the Enterprise would have been in the same place as it's prime-verse counterpart to witness the Enterprise-C arriving from the rift is incredibly iffy. The exact place it needed to be to put things right.