I think that these women prefer Rihanna over Beyoncé because they perceive Rihanna to be more real and authentic. They literally see Beyoncé as a privileged industry plant and Rihanna as the artist who started from the bottom and reached the top with talent and hard work. Actually Beyoncé is the most talented and professional of the two. She has Better vocals, better stage presence, better energy and better performances in her live shows.
To these women Beyoncé is too aspirational, secretive, orderly, corporate, perfect, boring, sanitized, machine-like, professional, they just can’t relate to her. She’s out of reach to them and they find it impossible to emulate her. In their eyes, She’s too good to be true. They believe artists are more human, credible and genuine if they go through struggles and rexpose their flaws, failures and bad habits.
Most women feel they can be Rihanna because her style/image/vibes/ethos makes her more relatable and accessible- copying her image is still within reach- another reason why they prefer her. It’s easier to become Rihanna than to become beyonce. Rihanna is openly sexual, more vulgar, and doesn’t even pretend to be a classy, pure and perfect woman- I mean she was actually marketed as the vulnerable good girl gone bad. That’s literally the title and theme of one of her earlier albums(the one with the international, career changing hit single umbrella, if I recall correctly)
Beyoncé is viewed as the standard of excellence and deep down a lot of women can’t reach it.
Also rihanna musical repertoire is much more pop/catchy/easily digestible for the average person. All her hit singles are catchy as fukk. Umbrella is a melodic ear worm, you hear this song once and you will never forget it again