IBM didn’t care about gaming, and neither did the early PC clone manufacturers. And early IBM compatible PCs were pretty shitty gaming machines compared to other PCs. And game companies used eye watering hacks to make their games work within the limits of the platform. PC dominance in gaming came after PCs became popular.
I don’t see how this is relevant. The PC gaming market was niche and immature at this point in time and developers were trying to gain traction. Today the market is massive and virtually all of the users and money is in the PC platform. There is no reason at all that Valve would waste money and developer time on supporting a platform that virtually nobody is going to use now or at any point in the near future. Valve is already doing great work with Proton and Steam Deck to get Linux gaming on par with Windows.
