So isn't having a separate channel for those 20 that change and update often but thus more prone to risk than the other 2480 packages that you probably would like to work and not bother you a good thing for your productivity and security? Now I last used ubuntu 2-3 years ago and IDK a lot about PPAs, but, what are the shortcomings, exactly? Clashing dependencies (i.e. sth. in your ppa wants libbob 2.0, but ubuntu has 1.8)? The packages you want don't have PPAs?
PPAs would work if they would be widely adopted by all the upstream software whose latest versions people desire AND the PPA infrastructure is adopted by all major Linux distributions so that developers don't need to package in N different formats. But as it stands, leaving it up to distribution maintainers means programs tend to lag several versions behind, while for faster updating each distribution has its own incompatible way, which means developers often give up and don't package at all and leave it to the maintainers, or just select one method like PPA or AUR.
As far as I can see, Snaps/Flatpaks aim to change this, but at the expense of introducing much less manual oversight and inefficiencies in terms of storage, at the very least.
I'm really not sure what you think I'm arguing here. The situation I have with Ubuntu+ppas is satisfactory to me, and it is also anecdotal evidence that "leave it to the maintainers" (asserted by the OP) is not a complete solution to real problems (my assertion).
