Not the commenter you're asking to, but ligatures, to me, are a print thing. They are not nice on the computer screen. I'm kind-of fine with fi and ffi with variable-width fonts, but the rest is geekery (which is fine in itself, but not practical).
With print, you have to think about kerning and the flow of the ink, and the DPI of the printer, and many other variables, and some ligatures help with that (fi). Then there are some letter strings that appear consequently very often (e.g. st), in which case if you're cutting your fonts out of metal cubes, it's practical to have a single character for those strings. They are not, basically, of help to the reader, but instead to the typesetter / the machine. But you don't spend ink or metal on a computer screen, so the ligatures are just there for the sake of it.
With monospace fonts, well, because there's no kerning (each character takes up equal space), there's no way that normally any bits of the letters could coincide, so all the ligatures are forced and artificial there.
Monospaced fonts simply mean that the horizontal width is constant. While this also means there aren't any kerning pairs, it is a different concept. Simply disabling kerning does not mean a font is monospaced.
Kerning is a table of pairs that allows them to have more aggressive advance values. For example, with a sequential 'V' and 'A', the 'A' could be moved closer to the 'V'. But kerning doesn't have anything to do with the fact that in a variable width font that 'I' is narrower than 'X'.
I guess I took your statement, "because there's no kerning (each character takes up equal space)" to mean "no kerning means each character takes up equal space". Maybe that's not what you meant with those parenthesis.
Not the parent, but I’ve had an issue where the fi ligature occupies just one character width, which looks very wrong with an otherwise monospace font. If the ligature is done right (resulting glyph is double-width), then I would probably like it.
Iosevka does not have `fi` ligature.
The "Term" variant is used for some restricted environments, like some Linux would think that Iosevka is not monospace due to it has glyphs wider than one space.
It has some similarities with Pragmata Pro (my previous font), but has evolved to have its own personality now.
I build a custom version of the font with this command-line:
This gives me:- Disabled ligatures (I don't like them for my coding font)
- Underscore below the baseline (it is called underscore, after all)
- Tilde and asterisk centered vertically
- Zero with dots through it
- Fira Sans style @ symbol.
Sample: http://i.imgur.com/Hq4X7oV.png