Fonts do have other features that were not much used in the programming/tehc world. but one example there would be support for ligatures, which could be a lot

Fonts do have other features that were not much used in the programming/tehc world. but one example there would be support for ligatures, which could be a lot more complex depending of the language you want to support. And depending on the rendering speed you want, you might want to perform some JIT compilation, which unfortunately might not cover all edge cases.