Shareware died before Steam. Steam launched in 2003 and didn't sell any 3rd party games until 2005. Nobody gave a shit about shareware in 2003. Nobody gave a shit about shareware in 2010 when Steam seriously became useful as a place to play more than the Orange Box and Counter-Strike.

I hated Steam when I first encountered it, but it's not a requirement to publish a game on PC/Mac/Linux. Nor is the process to install non-Steam games full of scary warnings like Google Play even on their own platform SteamOS. And they do let publishers give keys to 3rd party stores to sell unlike virtually every other platform. They aren't perfect but they are nowhere near what Apple does with iOS.