I'm just wondering how old this code is that it's still using OTF, given pre-woff supporting IE doesn't matter any more. I mean FFS are you actually testing on IE?

That and where's the WOFF2?

I do often laugh though how often people don't grasp that the weight and style declared inside @font-face is automatically applied with the specific font.

Or how if you set normal but not the others, the rendering engine can automatically apply its own rules to generate them and/or read rules from the font about that. A well designed font in its configuration data will include stuff like how many degrees of slant to apply for italic, or how much to widen the characters for bold.

Using specific fonts for each variation being artsy-fartsy nit-picking normal end users probably won't even notice or care about.