Well, yes, that's the joke.
'Love' to Ribrianne is merely a four letter word from which she appears to draw her power as she hypocritically judges others for shallow things, like ugliness, or rude conduct. She doesn't understand this, yet commodifies it. It's the shallow sort of love reserved for celebrities, all spectacle.
Let's just ignore how 18 punched through her powered up form like wet tissue and dodged Ribrianne's blasts point-blank.Love Power and its strength by Ribrianne and Universe 2 remind me greatly on how the Green Lantern Mythos seems to work as well, aka the emotional spectrum. The More Will a Green Lantern has or the More Love a Start Sapphire has from someone, the stronger they are.
Also, another important scaling factor for the 18 fight was that Ribrianne was shown to be weaken from continued battle and rough up pretty badly before she got her Giant Power Form Boast. Also it was not fully 18 that beat Ribrianne in the final battle, 17 stepped into help 18 out as well with running some defense. So Ribrianne's Upper Levels of power is likely a good ways beyond her fight with 18 due to the earlier stamina drain and how roughed up she was from the Tournament.
She also got duffed by Base Vegeta pretty easily.Since I explained where 18 got her Love Power from, I will explain now that Ribrianne and the Other Maidens Kakunsa and Rozie's Powers of Love comes from their Caring and Connection to their Friends and Universe by how it was shown in the Anime. These ideal of love where also shared by their Universe as well, 2 has the 2nd highest mortal level of the Universe in the ToP, usually meaning the Universe had great progress of their mortal's livelihoods and their civilizations. Most of their ideals that got them that high was base on their beliefs in these forms of love for each other and their champions, so the Power of Love for Ribrianne and her Universe was the Real Deal. It lead to the final fighters of Universe 2 getting a power increase from their Universe based on their Love and Beliefs in them that lead to the Black Love Hole attack in Episode 118.
https://www.youtube.com/watch?v=L9tfWTawCts
Also going along with this, Ribrianne earlier was shown to gain a Major Power Increase in Episode 103 after sadly Kakunsa and Vikal got eliminated and her love for them increase her power greatly to go toe to toe with Android 17 who was speculated to be maybe SSJ-Blue Goku tier before the ToP started. He was impressed by Her power as well.
https://www.youtube.com/watch?v=xGuCLDTCzUk
If he actually tried - ie, went Blue instead of conserving his stamina - it would have been a really quick elimination.
But again, jokes.