Out of curiosity, don't most systems that use .deb files already have Firefox in the package manager? I was under the impression that Debian now has mainline Firefox (instead of Iceweasel) as of a few years ago
Yes, but if you’re not running either the most recent version of a Debian-based OS, you either have to hope there’s a version in the backports repo or potentially break your installation through a diet-upgrade.
Getting the version from the vendor can be more ideal, since there’s no dependency on one party to keep another party’s software up to date, especially where distribution versions are concerned.
