A big part of the 30% is that people generally believe steam will not fuck them over. While everyone HATES literally all other launchers and walled gardens because they know EA et al want to fuck them over as hard as they possibly can, at every opportunity.
It also helps that the other launchers are terrible. There must be some hidden complexity of which I am unaware, because I do not understand. As a rule, slow to launch, memory hogs, unresponsive, etc.
This for a local application that has a library of…10k items in the entire store? The inventory could comfortably be processed inside Excel and yet the launchers struggle.
I don't know how absolute terrible the database must be, that you are talking about, but I think that managing 10k entries of whatever shouldn't be any problem at all for anything with a CPU and like 640KB of RAM.
It's extremely telling that nobody (developer or consumer) takes the Epic Games store seriously, in spite of their effort to undercut Steam on this front (0% on the first mil, and 12% after that - to say nothing of the free game promos.)
Epic has offered self-publishing tools for a while. They do involve a human review step, but one look at the piles of NFT shovelware available shows that the bar is in Hell.
(Granted, Steam isn't too picky either, but at least they draw the line at unregulated speculative assets.)
