I like to think being a homogenizing swarm is default behavior and the Borg just got really good at it. They’re still not as good as The Culture, of course, who make your biological and technological distinctiveness not matter. Or to put it better:

“Even the most urbanely sophisticated, scrupulously empathic and excruciatingly polite civilisation, it had been suggested, was just a hegswarm with a sense of proportion.”