If you don't want to sideload, then don't. If companies don't want to be on the platform app store anymore, it's not the end of the world. I ran a windows phone for several years; if there's no app for something, there's usually a website, and Safari is loads more usable than mobile IE or mobile Edge; so you're fine for the most part.
Yeah, you might lose out on playing FPS games on your phone, but is that really a loss?
The net loss is to society when Meta pulls Instagram from the official store and says "to continue using Instagram, go to instagram.com in safari and follow the instructions".
And they could close overnight from lack of millions of users.
Apple is not required to make it “download file and double click” easy, the best course for action would be making it relatively hard to enable so that no one’s grandma will be able to follow the instructions.
Yeah, you might lose out on playing FPS games on your phone, but is that really a loss?