I appreciate your reasons and desire to use a stream downloader like StreamFab, and your frustration with the situation. And I have my own reasons to use/rely on apps like StreamFab, which I'm sure we all have our reason/needs for it. And frustration doesn't adequately begin to describe how I am feeling about the current situation with StreamFab.
In a perfect world, apps like StreamFab wouldn't be necessary. Physical media would be available easily for those who have no or limited broadband access, just want the better audio/video quality available on discs, or want a copy that is theirs to KEEP.
That being said, your Points 2 and 3 seem like you acknowledge the streaming services, digital content creators, and lack of availability of physical media, are the gate keepers here.
Unfortunately the gate keepers implement DRM to keep people from downloading and freely distributing to others. The DRM is a lock, and apps like StreamFab are the lock pickers. The content owners update DRM to further prevent any "existing lock pickers" from working. When the locks change, a new way or tool to pick the lock is needed. Its frustrating, and even infuriating, that sometimes it takes longer than others to pick that lock again.
My hope is/was, that Fab would Focus on Amazon DRM issues since that is the highest used/visible downloader, not only for Prime movies but for all of the Amazon Prime Channels like Max, Paramount+, etc. And any other bugs would be low priorities until at least Amazon DRM was fixed. Of course we know that doesn't appear to be what is happening.
I don't know what the future holds for StreamFab. I'd experienced the demise of DVDFab DRM Remover for Apple/iOS, which has been in the back of my mind since late February. I don't want to imply StreamFab is dead or soon will be, I'm just saying that sometimes DRM is not breakable by software like DVDFab/StreamFab or others. I expect Fab fixing Amazon so it doesn't need the work around (re-encoding) at some point, I mean others have figured it out already so they should be able to. I just wish we had a clear window into the progress, and timeline. As for Netflix, I'm not so confident it will get any better.