You’re missing my point. If side loading and alternate app stores offer a bad experience it doesn’t need to affect you. Just don’t use them and you will continue to have the same ‘walled garden’ experience that you currently enjoy. If other users choose to use them and have a bad experience, that’s their choice!
That’s not my experience. I recently got in touch with them about some Jabra earbuds that were just over two years old and had developed a fault. I was prepared to quote the UK consumer rights act to them, but it wasn’t necessary. They refunded them immediately and said I didn’t need to bother returning them.