If all major browsers supported everything I needed in HTML5 besides just Chrome, then I would consider it. Maybe things have changed recently...I don't know. People who do HTML coding all of the time also like to suggest things like this, there is nothing wrong with it, but when you are a hammer, everything looks like a nail. Maybe I'm the hammer here maybe not, but I don't really care right now.
I see it in my profession all of the time, even when it would make more sense to use something else...people like to use what they know. I know people that swear by Pearl even though I think its awful (I still use it when I have to). Also, I don't think it matters, if the result is the same, what does it matter what language I use?
HTML5 is a perfectly valid solution, and something I may consider when the major browsers support what I need. I do have code I can work off for that if I do that as well.