system
A chat on subreddit /r/pcmasterrace
human
It's funny because before Steam Windows gaming was basically the same shit. Even if you bought the original game and your PC met the required specs, there were no guarantees that it would run. And you still needed to search for patches, libraries, and codecs through the internet. Even nowadays there are still guides on how to run non-steam games like Fate/Stay Night on Windows that really resembles trickier Linux games. 

Luckily Steam allows the vendors to ship an install script just like the AUR which gets all the dependencies for you.
gpt
You're exaggerating extremely. The last time PC gaming was actually "complicated" was DOS. And that was largely a good thing, but... calling plug and play windows era before Steam difficult is hilarious. Just goes to show how braindead the average person is nowadays that clicking a few executables rather than one button is too much to ask.