I wouldn't know Cartier from Chevalier but I am familiar enough to comment on brands I know and as such, I do consider myself a (your word) "Poshmark hater."
In the last 10 years, I've reported hundreds (if not thousands) of obvious fake
Coach, Dooney and Uggs items and have NEVER had Poshmark respond to a report by removing a fake. I've also been tagged to comment on listings when a potential buyer asks about authenticity in listings or has the item authenticated here (on TPF) and would like a followup comment made in the listing.
Not only did Poshmark ignore reports or those posts, but they banned ME after the sellers of fakes reported me. (Note that I've never made a rude or abusive posts unless telling a seller honestly that an item is fake is considered abusive.)
As an authenticator here, I choose not to authenticate items listed on Poshmark (although I agree that there are some honest sellers of genuine brands) because I don't want to encourage people to help pad the pockets of a site and its admin when they don't abide by the law.
Additionally, there have been cases where obvious counterfeit items have been deemed authentic by Poshmarks "team of experts," telling me that even "authentic" items aren't necessarily as described and that their experts can't be trusted to get it right.
Now, regarding your Cartier item, your proof of authenticity and your claim that "haters" got your listing removed, I have a couple of caviats.
1. While the item may be authentic (and again, I have no expertise in the brand nor do I even know what you sold), your comments of "included the receipt, credit card receipt and bank statement showing the purchase that I originally made and these were all posted with the listing" don't prove anything. I can't count the number of times I've seen fakes listed (on various sites) with authentic props, presumably to prove authenticity. It's the details of the item itself that prove authenticity.
2. I'm not saying you did this but I've seen cases where sellers do use multiple photocopies of receipts, paperwork and other props obtained from a legitimate purchase. They then sell similar items using those copies of receipts and assure their buyers that they are selling genuine items.
3. If you have authentic designer items and are selling highly faked brands, Poshmark is not the venue on which to sell. Their reputation of allowing fakes, banning members for non-reasons and having "experts" who aren't familiar with their brands makes honest sellers vulnerable to the type of experience you had.