[jacquesm]

Yes, because every kid (at least in the 'developed' world) nowadays has web access but not every kid can install software on the machines they are allowed to use (for instance in school, the library or their parents' machine).

[cakesy]

And, they can very easily show it to there friends, if it is in javascript. My niece loves designing webpages that she shares with her mates. Of course, getting her to program rather than put up pictures of twilight is another issue.

[netcan]

True. I guess these are the same two reasons anything needs to be web-based: (1)Easy to get started. No hurdles. (2) Sharing