For instance != is just a way to write something that looks similar to ≠. With ligatures, you can actually see the symbol you're representing, and not an approximation. I suppose that is the appeal. And it looks neat.
I think the flip side (which is why many people don't like them) is that with ligatures you can't see the actual code that you've written, only an approximation.
I do agree with the Butterick that when presenting code to others, for example as examples, the ligatures are a big no, because in this case you actually need to see what characters you need to input.
I won't be going around and trying to convince people to use or not use ligatures though. I feel that it is a very personal preference much like the choice of syntax colouring theme.
Iosevka has several presets, or can be completely configured: https://github.com/be5invis/Iosevka#ligations