Well, you have to understand that most of the places publishing pieces that say things like that are considered “generalist” publications, which means they are for a general audience, people who might otherwise not know much about hip-hop, nor be as in tune with the history of Jay-Z and the genre as a whole.
People who were around in 1996, who remember what was happening then, they know that Reasonable Doubt wasn’t that big of a record when it came out, that it was a slow burn, that it dropped around the same time as It Was Written (itself, just a carbon copy of Only Built 4 Cuban Linx). And though Reasonable Doubt may have matured a little better than Nas’ second LP, it was certainly just another rap release at a time when there were a lot of great rap releases. I mean, this was 1996. Every album back then was incredible.
Again, to your point, the average person writing stuff online these days has little reference for stuff like this, and I don’t even think it’s accurate to call it the first grown up rap record; but again, you’d have to be intimately familiar with hip-hop to know that, and these outlets and these writers are just not. For the most part, at least. It is what it is and we move on. It’s just words on a page that, ultimately, no will give a shit about tomorrow. Least of all Jay-Z.