Ok, are you posting just for the sake of posting or what!?
Which argument do you want or just choose both
1) last authentic material they wrote as a band, publicly acclaimed was UYI. Izzy was known to be the creative force, for not only co writting but taking lead vocals on some tracks too. Once Izzy left ad 6 years into semi reunion, the best they came up with was - Abs/HS. They can't craft a new album 7th year into 'reunion'. Enough evidence, now!?!?
2) yes Izzy probably main reason, creativly, but not the only reason. Each member '87-'93 had a purpouse why GNR became GNR and all those post years prove that.
Considering you have 25.5k of posts, I thought you will figure that out from the posts, but here it is.