It is a fact that the Mesa OpenGL support on Linux is currently a bleeding edge work-in-progress.
Now, I can understand getting a little annoyed when it breaks. I've experienced this myself. However, it has never upset me to the point where I have to vent in a long rant. And, it would be completely over-the-top if the rant is about how Mesa broke my compositing window manager, which is basically just eye candy.
And yet, that is exactly what the lead developer of KWin felt he needed to do. Some people take their eye candy very seriously. I liked the one response which suggested turning off the eye candy until Mesa is a bit more stable. Well, duh!