Arch does have a lot of that. Not all of it, but it does have clean chroot building, gpg signing, linting etc. Mostly, arch does less testing as the philosophy is "trust upstream".

However, none of this is required for unofficial packages. You can do it, but you don't have to. This is where I'm saying you're conflating two different things - QA and packaging are separate.

Please don't get me wrong, I love debian and they do an incredible service to the Linux community with their testing. But why force it all on users that just want to build a simple package instead of doing make install as root?