Generalists and specialists can also happily coexist.
I advise Startups to hire “athletes” for early hires. Folks who are nimble and flexible and who do well at almost anything they try. Basically, generalists.
Generalists don’t need a manual and can deal with ambiguity.
You’re right though — as startups scale, specialisation becomes a priority. Specialists, though, need much greater clarity, clear swim lanes, and an operational blueprint.
I’ve seen a pattern in startups where generalists build a team from scratch, get to the point where it has well-defined parameters, and hand over to a specialist. Then the generalists are redeployed to build the next new thing.
Always something new to build in a startup!