Two tendencies combine to make "parentheses" the Lisp topic that in sheer quantity dwarfs all other Lisp topics added together: 1. the human brain craves familiarity; 2. people love bike sheds.

(Bike shed = something anybody can have an opinion and argue about irrespective of knowledge or effort. Since their purpose is to jump into the argument, these opinions tend to be strong ones, diminishing the likelihood of any resolution. Indeed, a feature of such discussions is that they are argument for argument's sake, and thus no resolution is possible or even desirable.)