The ligatures for != -> etc. are a terrible idea, imagine someone reading a programming language tutorial or a snippet and then actually trying to type stuff rather than copy-pasting.
This is like saying you shouldn’t render latex. I like my ligature font, it makes nicer to read code for me, not terrible at all. Your programming font is a personal choice, i guess when publishing a tutorial you need to consider which font is appropriate, but that doesn’t make anything terrible.
I'm sure they're very rewarding for the author/editor - but the cost is externalized onto unversed readers, this is generally considered bad practice in other areas of programming.
I'm not a fan of ligatures. Don't like the idea to not have a source of truth when reading code/text. Text should be pure, I find that ligatures obscure intention when I read code. I've tried using them, but they just look weird to me and I have to stop my reading flow and reason about a given ligature. I'm pretty sure it's just habit, but I never pushed myself to use them for long time, never felt the need to train myself.
It's for programming with English based programming languages, not regular arbitrary text. I do think there should be more language specific programming languages, but since there are not, there is no reason for a programming font to support it.