Vandalism is a stupid word to use. I imagine the process went something like this: "I wonder what happens if I add $.fadeOut() as the text of the question" "Oh crap, it worked". This is called experimentation. If you're in chemistry class and you mess up a lab, you're not accused of vandalizing apparatus... it's simply what happens when you are trying something out. Similarly, when you have a text box on a test websi…
Your chemistry class example is nonsensical. In class, if there is an opportunity to explore a few things and a mess is made, maybe you would not be blamed. That's usually not how labs are run--you follow a procedure and mixing chemicals with no forethought is a huge safety hazard to everybody in the lab. Neither the "real world" nor the Internet is a place with a mutual agreement between all participants to experime…
No, a better example is going into your backyard, shining a flashlight onto your neighbor's shrubbery, and then having the neighbor complain to you about changing the shrubbery's color from black to green.
The protocol for a shrub is: you shine light on it, it reflects light back. The protocol for a public web service is: you send it an HTTP request, it sends an HTTP response. If you don't want your neighbors to see your shrubbery, build a fence. If you don't want your website to contain arbitrary scripts, don't let users submit arbitrary scripts.