- I see "stores" such as Flathub or App Store mostly as infrastructure, and infrastructure should be a commodity. Still, whenever you can choose a supplier for a commodity, you should make a conscious decision based on questions such as "are you really 100% renewable 24x7 or are burning coal to handle the peak". Blog posts such as these should be a part of Flathub's official "propaganda engine", so that (potential) users get exposure to the outlined problems.
- You can provide users with certain strong guarantees about what your review/testing/distribution process will or won't allow, which sets a minimum baseline of trustworthiness for each and every single app. This can be extremely powerful; I trust Apple's store much more than I would ever trust Google's, solely based on the values both companies represent; however neither of them could ever hope to be as trustworthy as Debian.
- Providing a paid builder service to proprietary apps could be a strong incentive by itself, and help the bottom line. Apple launched a build service, but infamously does literally nothing at any and every stage to help accommodate FOSS apps in their ecosystem. What if Flathub could get one step ahead, and show everyone: "OK, you have a different business/source access model, we recognize that, and we're willing to accommodate you". I feel that it has the potential to generate a lot of goodwill from both users and developers, and then also influence the industry at large.