Thankfully long before that. I recall Diablo 1 was released for Mac OS (9?) only a few weeks/months after PC, and Warcraft I and II had full Mac Support!
IIRC it was't purely a post-release-port, they did have parallel development tracks before anything was released and for some titles they didn't want to risk the upfront cost for the relatively small percentage right away.
Warcraft 2 was my first experience playing a cross-platform network game. I was on a PC and I dialled in to my friend’s Mac. Understanding how things are architected now it makes perfect sense, but as a kid my mind was blown since I considered these to be wholly incompatible platforms.
Too bad the GPU race has left Macs in the dust.