Its not a question of whether he can rap, put words together, ride a beat, etc. These are all things that can't be denied. What has kept him from putting out "that album" has been artistic direction. He hasn't gotten that from Dr. Dre in years (given all of Dre's ventures outside of music, and his own self-doubting about his own material), Rick Rubin oversaw his worst projects, and while he is highly regarded in music....it just wasn't a good pairing.
Having someone be the executive producer of a project, overseeing everything, helping to pick out the tracks, album art, marketing, etc.....people tend to overlook the importance having someone like that is.
Having the longevity, experience and clout that Em has earned throughout his career, sure he should be able to put a project together himself.....but some people like him need direction from the right executive producer. Not having that.....and having yes-men tell him everything is all good has hurt his legacy.
He has it in him, but unless he puts his faith in the first person to coach him in the booth.....we'll keep coming back to this argument.