No one needs it, but it's nice to have. It's the difference between being partially or fully colorblind or not being so, in terms of being able to distinguish parts of the codebase more easily. That is what the parent means by "easier to parse code."

> I like cursive though to highlight variables that are assigned more than once

Exactly, everyone is different, as personally I'd hate cursive and ligatures. Think of it as, what works for you doesn't work for everyone, and what works for them (color) doesn't work for you. But let people have their preferences.