It's not a matter of whether I'm chill or not and I'm not sure if there's any meaning explaining this to a random individual among the vast internet, but I'll do it anyway.
In a sense, it's true that MAL ratings don't represent some regards of the community. For example, it's true that Nami is a popular character and probably moreso than Robin. What this website does, though, is calculate the actual appreciation a character receives from the fanbase rather than simply counting down the popularity. But, even with that in mind, Robin has way more votes there so it's easy to find out her amount of fans. It's not like there is a rating like anime/manga titles, what decides the ranking are the favorite numbers. This is quite obvious when looking at the BNHA cast.
Second, these "ratings" might not be accurate when comparing characters from different series. That much is true. Subaru from Re:Zero is definitely not seen as a better character than Usopp, for instance, despite having 1k favorites more. Although, considering he's one of the most promiment characters of his own universe and the smaller cast, this is a natural situation. It becomes way more indicative when comparing characters from the same series and Nami definitely has a low position there. I mean, she's even lower than Chopper, who has been absent from the storyline of years. Brook, Katakuri, Carrot and Sanji got elevated so much after the Whole Cake arc and yet Nami stayed behind despite being labelled as the second MVP by the hardcore fanbase. MAL has all kinds of anime fans and is the most popular site for listing favorite anime and characters. If such an environment isn't indicative of the general anime fans' opinions, I honestly don't know what is. Especially when realizing that One Piece is a highly regarded series there, the manga holds the 5th position in rankings.
What you say would make sense if my last point wasn't the case. The OP anime has almost 74k favorites despite being hated upon the past years (imagine what a OP-friendly environment we're talking about) and the manga 53k, which is insane for manga statistics. Now, you can compare this massive hype with the 6k favorites Nami has despite her screentime, role and "popularity". It's not that hard to figure out this situation anyway. In pretty much every single thread of this kind on this sub, Nami is being called a "thot", a "boobs" and a "bitch" the first chance given and those types of comments receive insane amounts of upvotes. Perhaps MAL is accurate in the "appreciation" aspect. Yeah, your own joke was probably milder than others I've seen but, you know, this has become ridiculous and tiring. If "popularity" equals to the 50k tags of sexual content on Pixiv, then she's definitely a popular character.
I could keep on analyzing this matter with MAL and give more examples but I've grown totally bored out of this. You clearly haven't searched as much into this as I have and that's okay. And... inb4 you call me out for writing paragraphs for a fictional character on a sub meant to discuss fictional series and characters.