I would agree with the comment you're responding to, too often in tutorials or especially in off hand comments here, I find their usage to assume some common but unindicated convention or subtext and obscure the concept they're trying to convey.

They’re the programmer equivalent of ‘x’ and ‘y’ in mathematics — which programmers don’t use as generic variables because they’re used for “math” embedded in code such as coordinates or measurements.

> distinctly pronounced from each other

This isn't so much of an advantage for "bar" and "baz". Those sound pretty distinct to Americans, now, but "r" -> "z" is a known type of sound change, which implies that for some people they'll sound the same. "R" -> "s" is attested in Latin, presumably because "z" wasn't an option. (Latin fricatives don't have voicing distinctions.)

For an only slightly different current example, the second consonants in "virile" and "vision" are perceived as distinct in American English, but identical in Mandarin Chinese, which is why the sound is spelled as "r" in Hanyu Pinyin and as "j" in Wade-Giles.

Show me a phrase and I'll show you a language it doesn't work in.

Is there a language that identifies "ta" and "pa"?

It’s the same idea that drove Lorem Ipsum for type setting placeholders.