I'm going to start submitting stories like "${trendy_website} breaks ${random_official_sounding_standard} with ${what_can_break[random_official_sounding_standard]}" and link it to a post on some newsgroup. My karma will go through the roof.
Quoted-printable breakage is not a major problem in the long run, but if there isn't a good reason for the violation, then why not fix it? It may have just been oversight.
I used a provocative title because I wanted people to read it, mod it up, and allow fb engineers the chance to speak for themselves. If no one found it compelling then it wouldn't have garnered any karma and you wouldn't have seen it.