That is not always possible. When the project is built on extensively modified server, rewriting it again is a hassle not worth doing.
Maybe extensively modifying the server was simply going the wrong way?
No, it was the right and the only way. Working on custom product will do that to you sometimes:)
That's something misleading with Open Source: It sometimes looks attractive to leave the code stream but it's not in the long run...
So your rant does not seems appropriate to me.