They are saying that those particular fonts with that particular kind of font-rendering engine (windows), doesn’t work for them for that particular language.
Sure, but if you read their comment, it is conditioned on all of those aspects together. It's not about the language, as is, but all of them together. Is it a useless comment? absolutely! But that's beyond the scope of this conversation.
I work at Microsoft, so I'm biased, but C# may be my favorite language I've worked with compared to C++, Python, Type/JavaScript, Java, C, etc.
I see/hear jokes often that it's Microsoft Java, and yeah definitely granted that it comes from the same origins, but it's got some of the greatest tools I've worked with, best documentation, and best support I've seen. Anytime I've asked myself "Can I do this with C#?", the only times the answer has been "no" is when looking for a C++ constexpr equivalent (closest you get is build-time code-gen, which ain't half bad), or discriminated unions (inexplicably).
I'm convinced that anyone who complains about C# has never used it.
But C# is extremely beautiful, you can read and write it like a novel.
Segoe UI is also not the worst font. I give it a 7/10.