At some point, depending upon why they're buying, I think having fewer employees is a bad thing. It means whoever is acquiring you has to do more work to turn it into a fully fledged business. At least that's the sentiment I heard when our startup sold (4 employees total).
It's no secret that the "going rate" for startups that are successful and get acqui-hired is $1-2M per engineer.
It's hard for big companies to find talented engineers, and so when they acqui-hire, they can just instantly shuffle those smart people out of the project they're working on and onto something else.
The bet is that each smart engineer will provide at least $1-2M of value to the company in the long-run.