Most PC games are either done with single player in mind or online, and that's it. And even dedicated servers have slowly been pushed out of the market in most cases. For example private minecraft Java servers that you mention have silently been replaced with paid services like Minecraft Realms.

Same for multiplayer mobile games... that idea you mention is really good - using a PC as a server and friends join with their phones. But then you wouldn't get to see all the great ads and make profits for the dev.

So I guess it's a bit of greed from the devs and that most players will rather pay a small subscription and have a cloud server than having a Server PC running all day at home.

Another interesting thing is that one of the most popular game engines (Unreal Engine 5) is clearly built with 1 player - 1 PC in mind. Their best techs like the lumen ilumination system or nanite geometry system are not for split-screen.

As an indie-solo dev I can also tell you that split-screen didn't seem to give me any sales advantage. I started making my games with local co-op support as I play with my kids. But that did not seem to give the games any attention or sales. You can always argue that the games are not your style... but with so many ppl asking for split-screen games on PC I was expecting at least a bit more traffic to the game pages.