Amazon thought it could compete with Steam because it was so much larger than Valve, but Prime Gaming's former VP admits that 'gamers already had the solution to their problems'
The biggest advantage Steam has over other platforms:
They're not publicly-traded, meaning they are inclined to look out for long-term success vs. short term profits.
Steam is already on their systems, and may have been for 20+ years. Nobody wants a dozen fucking game launchers and Steam already has virtually every game in existence available there. Not to mention the "community" features, friends lists, etc. Every other platform is simply too late.
They have 20+ years' experience learning what gamers want and implementing it.
Amazon could probably compete with them if they really wanted to, but that would involve a large, long-term, consumer-centric investment, which probably isn't a good use of their money.
#3 is the key I think. Valve's business model is figuring out what their customers want and then providing it to them. Amazon's model is to capture enough market share so they can start the enshitification process.
I bet the fallout with Vivendi and the lawsuit that almost bankrupted them taught them a major lesson to never be beholden to outsiders and thus never go public.
I can see how you're trying to justify a bad mangling of an analogy.
If we follow your modification of your modification of the analogy, you want physical cases for your games, which has nothing to do with launchers at all.
Though it seems you don't want launchers at all, you want independent executable files, which isn't what a launcher is in this context.