While it's a thought provoking question, I'm assuming it's because she's a talented multi-award winning musician - which is exactly Amber's point.
Speaking at SXSW (where she's promoting new ventures, such as lending "her likeness to the Zoobe messaging app" as well as detailing her annual #SlutWalks), Rose said: “It’s bullsh*t, and this is the thing: They come at me and Kim so hard because I was a stripper and she had a sex tape. So if we could sing, it would be OK if we were on stage half-naked. We all love Beyonce, but she’s on stage half-naked and twerking all the time, yet people say, oh, she has talent so she’s able to do that. We don’t have the talent that Beyonce has, so we get criticized as former sex workers, but at the end of the day we’re just women - we’re all women - and we should all embrace each other. No one is greater. We're all the same."
At the risk of getting shot down, I'm going to say we are indeed all the same (and yet we're all unique too), just some have more to offer than others.
As for Amber's stripper past; according to Uproxx she "doesn’t understand why Channing Tatum is considered a respectable actor when he’s a former stripper much like Rose.She points out how everyone mentions her with 'stripper' as a prefix, but Tatum easily slid into respectability with a few semi-serious movie roles. I doubt Rose even minds Tatum as a person, for she’s simply weary of the double gender standards."