- there are more fonts without ligatures than there are fonts with ligatures.
- every single OS I can think of include by default a monospace font that do not support ligatures.
- there are still a huge amount of terminals which do not support them.
- for almost any font that has ligature there is a variant without ligature
- there is virtually no way to end up with ligatures without actively looking to get ligatures.
- any terminal/editor that supports ligature has a setting for that.
- most people do actually like ligatures which is the reason they use those editors/terminal/fonts and want those activated by default.
Presence of ligatures in a "font designed for developers" is neither a plus nor a selling point. It is a pointless embellishment that shows that fonts' authors don't grok the character-oriented nature of computer languages. So them parading ligatures as something desirable only serves to detract from the rest of the font design and to nick their credibility as coding font designers.
> fonts' authors don't grok the character-oriented nature of computer languages.
Hogwash. They provided all the characters (which ligatures are also, but you seem bizarrely "against" but "for" the ASCII ones), and ligature-less versions as well. So they grok it at least that far.
For what it's worth I also have ligatures disabled but I do think it's fair for fonts to include them, particularly because it makes the fonts more versatile in settings where you want them.
In particular when doing presentations having fonts that are capable of producing ligatures in monospace contexts is quite useful.
I would concede your point if these folks were trying to sell you a used car.
You don't need to take their word or rely on their credibility for anything. There's a demo right there of the font for you to decide if it's for you or not.