Developers on the Facebook Platform ran into this problem a few years ago. Facebook had a bunch of style tags in their source already -- it seems like they put them in different pieces all over the place.

When you would write an application (your FBML is put into their layout) and use even more, you'd eventually run into this limit.

I think they fixed it by combining all style tags in applications into one, since they had to parse them for security reasons anyway.