#2 They've been on RAW and SmackDown almost every week since May
This is more a function of how WWE does things as well as who is available to push due to COVID-19 restrictions. The two top female stars in WWE, Becky Lynch and Charlotte Flair, are both out for different reasons. In their place, WWE has pushed Banks, Bayley and Asuka.
While the Empress of Tomorrow has not been on every brand in WWE, the Golden Role Models have. They haven't been on NXT that much but they do appear on RAW and SmackDown every week. That happened even before Banks won the RAW Women's title. While there are still plenty of talented women to push, (Baszler, Ruby Riott, Asuka, Sonya Deville, Mandy Rose, Naomi, Alexa Bliss), most of the spotlight has gone to the two Horsewomen that are available to WWE at the moment.
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A big part of why some WWE fans tired of both John Cena and Roman Reigns was that not only did they prominently appear on programming all the time but they also always won. They were pushed to the moon at the expense of almost every star they feuded with and it let to resentment from some fans.
Without fans, we don't get to hear the actual crowd response to Bayley and Banks, but they are heels and would be booed anyway.
Too much of one or two stars can sour some fans, especially with plenty of other performers that could get air time. If Banks and Bayley both drop their belts, it will hopefully allow some other women to get air time.