Why? Hybrid systems were and still are common. Today a common IT setup is Macs connecting to UNIX servers over the network.
I think it was more about Macs not being used for scientific applications much until the 2000s. Up until a bunch of programmers up and switched to MacBooks, Apples were more usually used by more artistic types. They were quite big for writing and art stuff, then, mostly, though pricey. And no separate monitors.