[quote=@Amaterasu]
Now that I think about it, didn't the characters start using flames when they received their rings? Looking back on the Varia arc, I don't think they were able to use dying will flames except illusionists cause they're magical fairies. Plus Tsuna. And Xanxus.
[/quote]

Yeah, nobody used Flames pre-TYL except Muku and Bossu.

But we're in the future so that shouldn't be as much of a problem.