I tried to do this, didn't get past validation stage. A lot of developers were hostile to the idea. This was around 2010 though. I didn't expect Steam to survive with that kind of hostility but it did. It's not even a shitty incumbent like WhatsApp, it's genuinely changed how we purchase and own games.
You'd probably have to do the Epic approach to even have a fighting chance: give out AAA games every month. Or the itch approach: lower the bar completely.
Yep. It's the classical critical mass problem: no users to attract publishers, no publishers to attract users. You need money to jump-start it, and we didn't want to seek investment.
Our plan was instead to create a solid client that integrated all of the other platforms into one, without even needing to have them installed. But out of the hundred or so people we asked, I could count on one hand how many actually cared.
If it had been successful wed introduce our own store as just another backend, low dev cut so we'd compete, and then subsidize sales with some investment later on.
It just didn't pan out. Steam has a death grip on the market despite having terrible software.
It's the streaming service problem. Entrepreneurial me wants competition and a free market, but end-user me wants everything on one service because bugger having 10 different game launcher/library apps installed.
You'd probably have to do the Epic approach to even have a fighting chance: give out AAA games every month. Or the itch approach: lower the bar completely.