> Was going to say about the same - this is ~2500 years after construction of the pyramids.

The first Egyptian pyramid known was built ~2780 BCE, the alphabetic writing in this article was from ~2500 BCE. That’s a gap of ~250 years, not ~2,500.

> How do you coordinate something that massive without any form of writing?

The Egyptians at the time of the Pyramids had writing, but it was logographic (symbols directly represent a word/concept), not alphabetic (a small inventory of symbols are combined in different ways to represent words/concepts.)

An alphabetic – and also phonetic – script is a big advance not because of what you communicate with it, but because if you know a fairly small set of symbols and their phonetic interpretation, you can encode a spoken language in it in a reasonably intelligible way to anyone who knows the same script (and you can even encode different spoken languages in the same script intelligibly, if they have a similar-enough phonetic inventory.)