But even in older times there was usage of terms like "the academic community" or "the gay community" or the "feminist community" ...

Academics used to meet in person frequently in order to coordinate their work, and they still do so to an extent, so they naturally referred to academia as a community in the local sense. The usage of the term "community" by feminist and LGBT activists was politically motivated; it was intended to underscore the fact that women or LGBT people did really share significant bodily risks as a result of their relatively low status, and that they could only protect themselves from such harm by engaging in political activism and opposing their purported "communities". Clearly, this does not apply here; by and large, LW readers are not risking bodily harm in their local environment as a result of being rationalists.