The difference is that it's not the case that a majority of chemists are ignorant about carbon, or geologists about bedrock, or astronomers about primordial stars or physicists about quarks.
Lisp is like an entire branch of computer science, about which a lot of people in computer science are ignorant.
Allow me to gently disagree. Most computer scientists I know are not ignorant about Lisp. Some scholars consider computer science a branch of mathematics, while others avoid such broad generalizations, as modern computer science has evolved into a broader discipline.
It's just that the majority of modern programmers are not concerned with mathematics, and that's perfectly acceptable. Mathematics itself has so many different levels that even mathematicians themselves are not always certain if they are indeed practicing mathematics.
You may be conflating programmers and computer scientists, but this could also be a perfect case of selection bias, where both of us are simultaneously correct and incorrect in our assertions.
Lisp is like an entire branch of computer science, about which a lot of people in computer science are ignorant.