I'm not sure I get your argument. You actually want to have to look at the "scientific" section of multiple stores for your specialized apps instead of one? You also state login as an issue, while I see that ZDN allows direct downloads do you really believe that alt-iOS stores will give up their chance at your personal info by not forcing you to have an account? This might work for some really specialized small apps but in terms of games? Tell me that the Epic app store won't force you to login? Any app that you need to purchase will require a login or your personal info to be provided.
I still highly value the one stop shop, its what I, and many others bought into, we voted with our dollars!
If you don't like what Apple is doing, vote with your dollars and go elsewhere. If your segment of the market is large enough Apple will change their policies. Forced legislation will not end well for any of us.