In one of the articles you posted is the following quote:
"While the definition and membership list of men's basketball's blue bloods are in flux, depending on who you ask and when you ask them, whichever 2022 NCAA Men's Final Four participant adds a fourth, sixth or seventh national championship to its trophy case, it'll certainly renew its membership application to the sport's club of blue bloods, thanks to a shiny, new trophy."
Sounds to me like the authors believes there isn't a definition. Its basically made up by journalists over time. And he said as much throughout the article.