Even if this is small progress the headlines and framing of the story are still doublespeak. Installing applications on your computer is the normal state of things. Walled gardens and not having control of your computer is the new weird thing. The word "sideloading" is a feudal concept and it's unquestioned use is dangerous for society. Properly stated this story title is, "Installing applications on iOS 17 might be…
Even on Windows if I send an EXE or MSI of my software to someone they get a scary security warning that prevents them from running it. The only guaranteed way around that is to be a big company (or a big open-source project). If security really mattered, every OS would run applications in a proper sandbox, but why bother with that when you can just point your Web browser at a program running on someone else's server…
these OSes were designed decades ago, before we really had a good grasp on security. there were other significant concerns as well, such as performance
also, modern OS toolkits, such as on macos and windows 11, are moving towards a permission and API model that will allow sandboxing. In fact, macos is moving quite quickly towards this.
And lastly, there is a widely deployed OS that runs all applications in a proper sandbox: chromeos
I think it's understood at this point by everyone in the industry that sandboxing is the future, but it's taking a while to get there.