The author points out two problems, which both are ridiculously obscure edge cases: if there’s
really a Unicode arrow in code you deal with, it likely won’t matter much if there’s an arrow or something closely resembling an arrow. The second point recommends getting rid of ligatures entirely just because they may, in some situations, do not display the right thing.
Both arguments ignore the 99.9999999999% of times ligatures do what they’re supposed to, and help me identify some symbols quicker. I’ll happily accept being confused once in a year about a strange-looking arrow in a debug log output, or from a weirdly rendered arrow in some ASCII art print.
People complain about weird stuff.