[1] Not exaggerating: https://bugzilla.mozilla.org/show_bug.cgi?id=390936
I suspect that set is precisely equal to the set of projects that just close bugs en masse after a certain date.
As a developer, this destroys the credibility of Firefox when it comes to interoperability, and in the outside world I have been perceiving a rise of Chrome-only web applications, this can't be a coincidence.
As far as web compatibility and standards, the inconsistency is part of Mozilla. Is Firefox a tool for open web standards advocacy? Some in Mozilla feel that way. Do we just want Firefox to render things well? There's a whole team for that too (https://wiki.mozilla.org/Compatibility). And of course there's Bugzilla, which can feel like a lottery – it's very hard to know who you encounter when you enter the project through there.
This stuff is hard, and making the right choices is hard – I'm sure Mozilla has not always made the right decisions, but I personally prefer ongoing struggles to make the right decision over a consistent and credible stance.
There is in fact a middle ground between "free for all, implement whatever you want" and "implement only what is precisely required by a standards document". In fact, this middle ground is the only way to make a practical browser engine. The two extremes are untenable.
There are definitely some 10 year old bugs, just like there are funny, off-topic, celebratory bugs (https://bugzil.la/1000000). Like callahad said, you can tweak your email settings, and the bugzilla email headers are super easy to filter on.
