It's worse than that. Firefox will download non-free javascript and html from pretty much every website you visit. Debian team needs to get on it, fast!
A substantial user and developer base prefers Debian precisely because of these Guidelines. Inclusion of free software (as-is) that automatically installs non-free binaries would violate almost all of these guidelines.
An analogous situation would be the non-free NVidia blob. Debian fully supports installing it, but it would be very much verboten to do so by default, automatically.
And your browser will download linked javascript from third party websites to make it run. As firefox downloads a codec from a third party to make the media you've requested run.
I actually agree about the conflict between this codec behavior and the Debian philosophy. But they need to come to terms with the much greater conflict with their philosophy that the modern internet experience presents.
Stallman, for all his faults, was right about a lot of things. We live in a world where people don't own their own books, and buy software on a subscription model. For a few years back in the late 90s and early 2000s it looked like free software was the answer. But the internet made an end run around it, and Debian, etc., hasn't caught up. We're all digital renters instead of owners.