I learned about Carbon maybe three years ago. Back then the README example looked like this: https://user-images.githubusercontent.com/10369094/30791512-...

Now it looks like https://user-images.githubusercontent.com/8397708/63456416-b... complete with weird cursive font and all.

IMO this niche obsession with cursives, ligatures and stuff in programming fonts actually hurts first impression for a significant percentage of people landing on this README.

I agree the ligatures are a bad idea, and I use a ligature font in my editor. I quite like ligatures, I find they moderately enhance readability, but you need to know exactly what they are for it to be useful: readability can't come at the cost of precision in a code sample.

In terms of fonts, what’s the difference between readability and precision?

Readability of programming ligatures is very different for people who are familiar with the language/font, and people who aren't.

For instance, look at the list of ligatures for Fira Code[1] and without referencing the monospace counterparts on the right, tell me if you can tell how to reproduce each one without a lot of guesswork.

[1] https://github.com/tonsky/FiraCode