In many programming languages, ≠ is not going to be a valid operator. In languages that allow unicode identifiers, it would be a bizarre choice to use ≠ inside an identifier, so you shouldn't have to worry about that case either. This holds for pretty much every other operator that gets a ligature. This only matters for languages like Agda, in which case just.. use a different font. You might even be able to automate this depending on your editor.

> They’re guaranteed to be wrong sometimes.

This is true (for example, in C++ I've occasionally had `>` be ligature-ized when it wasn't an operator and was just the end of a template, like `Foo<Bar>`) but it's never really been much of a problem for me; it's easy to ignore.

> If you don’t believe me, try it for 10 or 15 years.

granted I've only been using Fira Code for more like 4 years or so, but I've always preferred it since I've been using it. I really think this is just a matter of personal preference.

> So if you’re preparing your code for others to read—whether on screen or on paper—skip the ligatures.

This I can understand. Ligatures would probably be likely to cause confusion in people who aren't used to them, so I agree that in that situation it's probably best to leave them out.