Chicken and egg perhaps; as a Java contractor back in the day, I noticed the eventual creep of Ruby on Rails stealing some of it's limelight, then JavaScript or whatever the new hotness became (not saying JavaScript is in any way hot there).

As a contractor, I was compelled to learn those technologies because the companies were demanding these skills, not because I had a desire to learn another scripting language or whatever. Of course, it's often (senior) developers within the company that push the new, less-well-travelled technologies and the cycle repeats.

I guess the lesson is, don't let frontend developers dictate that JavaScript should be on the server, or is in fact a good language for desktop apps and so on.

Not sarcastic - just going for a low-hanging pun.