[meerita]

That's not a drawback at all. First, you would replace those font-bold with font-italic (assuming you name the utilities like that) and problem solved. You don't need to change .font-bold and add font-style: italic; in the font-bold class. That's they convinience of utilities: they aren't mutable.

[welly]

What if you have 500 pages which need to have font-bold replacing with font-italic? Or more? 1000 pages?

Sure, you can probably write a script but if you name your elements semantically, you potentially only have to change it once.