I think it's about what's freshest on the mind, like I said...they're overly-factoring in his recent shyt when talking about the G.O.A.T.... imo. In the last 3 years from Nas we have Nasir, LT2 and KD...lyrically all of these are, generally speaking, extremely mid (KD is fire but it's more so musically fire than showcasing his skills fire). I didn't even want to bring up Jay-z...but if you look at Jay-z's recent shyt, he is still super nasty, sharp af with the bars/flows, etc... Jay Elect did his thing on that album and Jay-z still pretty much owned the album, lol, showed there's levels.
So yeah, first impressions are important but last impressions are much more lasting, fortunately or unfortunately.