I don't know what you mean by "real NWA fans" but I agree and disagree.
I think your problem is that you're equating popularity with ability...when it's completely separate here.
I agree that Ren is dope...arguably the nicest lyrically. I remember those days well, and I had to look up his record sales....300k in the first week isn't a big deal, neither is going platinum after 25 years. I paid no attention to him once Dre officially left NWA
In 1996 his second album sold 30k in the first week, and his 3rd album in 1998 went 170k total.
Anyway you slice it...that's weak. In the 90s is was far far easier to go gold and platinum. When you compare it to what Dre and Cube were selling...that's trinkets.
As for popularity...no one thought of him as being as big as Eazy Cube or Dre and like it or not, they were the face of the group. Ren, while nice just wasn't. DJ Yella wasn't a big deal and no one talked about Arabian Prince.