> But I've just never heard anyway complain about "noobs" installing deb packages. Ever.

it is literally in the debian documentation: https://wiki.debian.org/DontBreakDebian

> One of the primary advantages of Debian is its central repository with many thousands of software packages. If you're coming to Debian from another operating system, you might be used to installing software that you find on random websites. On Debian installing software from random websites is a bad habit. It's always better to use software from the official Debian repositories if at all possible. The packages in the Debian repositories are known to work well and install properly. Only using software from the Debian repositories is also much safer than installing from random websites which could bundle malware and other security risks.