demographic parasite

demographic parasite (noun) dem· o· graph· ic par· a· site | \ˌde-mə-ˈgra-fik , ˌdē-mə- ˈper-ə-ˌsīt , ˈpa-rə- \

: A person, social group, community, nation, or broad grouping of people having common traditions, institutions, and collective activities and interests that resembles a biological parasite in living off of, being dependent on, or exploiting another social group while giving little or nothing in relation to the dynamic balance of a population especially with regard to density

A community which maintains its level of population without breeding from its inherent genetic stock is a demographic parasite which requires replenishment from other communities to do so.

Fleeting Demographic Rule

1. A gimmick or storyline may be reused freely and safely after a few years of dormancy.

2. The unwritten rule that, after a given number of years, there has been enough turnover in the fanbase that a writer can re-use the same gimmicks and storylines with impunity.

The fleeting demographic rule allows YouTubers to reuse jokes and catchphrases after they have become repetitive.