I would say the process on getting "maintainer" status.

That they work reliably?

They work reliably with a lot of unseen work. Debian is a great distro as a user. The .deb packaging tools I found to be a huge hassle and made packaging up missing or updated or custom software a pain in the ass.

Exactly, this is why it takes literally years of human effort to get a new version released

Have you built a .deb with debuild and debhelpers? Can you recall all the goofy rules about what needs to go in each file and what each debhelper does? How do you keep all of it in version control and build downstream packages that depend on the changed one? Have you managed to accidently sneak a local build machine dependency or piece of information by accident into the final .deb only to realize it much later?

I found it be a big ball of easily forgettable twine of rules tools and oddities myself that every time I needed to redo something was a hassle. With many foot guns that lead to odd package issues.

Completely agree with your assessment of the building process. The majority of the complexity involved in the process is not inherent