Because javascript has a number of serious flaws. And because when you bolt everything back on to node to get a decent webdev environment it's really not that

Because javascript has a number of serious flaws. And because when you bolt everything back on to node to get a decent webdev environment it's really not that fast. And because callbacks are a really shitty way to write async code. Like most things node is a tool with a very specific use case, as is typical with anything that is particularly fast at one task people assume that it's fast at all tasks. (C anyone?) And also because unless you are running a free service your code really has to be absymally slow to not make money. Therefore you should program in the environment that is most pleasurable rather than the environment that is 'fastest', whatever that means. But mostly because most of the people who talk about how great node is really don't have a clue what it actually excels at. Basically, for all the same reasons people hate PHP.