The story is as short as this: They are now putting everything in. They even claim that “The users want that!” They are following the dark path Freefont went.
But to quote Behdad, “No, that is not users want. Users don't know what fontconfig is, users don't know how font selection is done, users don't know all these things. What users want is that their software works. If the simplest way to give them that for you, the font developer, is to stuff every glyphs somebody contributes into a single bin, this bug is the result, let everyone suffer it.”
The story in detail appears on gnome bug 334758 (continue and read all the comments), where Behdad and Owen, the pango maintainers, are trying to talk sense into the matter. Matthias even tries sticks and then spelling out the terms, but to no avail.
I didn’t know about this until it bit me today: I started to see ugly Persian fonts appear on my Persian GNOME desktop. Running $ fc-list :lang=fa was the answer. DejaVu Sans was there, while it shouldn’t have been. (I was even worried at first that some copyright-ignoring Iranian has contributed the glyphs, as they looked somehow Tahoma-like, but well, apparently they were original contributions by Ben Laenen).
It’s so sad. I just ran # yum remove dejavu-fonts.