I thought programming fonts are typically monospaced, which means collisions (which create the need for ligatures) aren't much of an issue. I agree that ligatures aren't good in programming, but it just seems the need wouldn't be that great. Or am I missing something?
Ligatures in programming fonts usually don't want to solve the problem of character collisions. Instead they transform rather weird symbol sequences used in programing to something closer to symbols used in maths or how you would write it by hand, e.g. != becomes ≠, =< becomes ≤, or === becomes ≡. More examples are in the repo readme: https://github.com/tonsky/FiraCode