Maybe it's because there's 1000X more competition now than before streaming.
Take it back to 1989 and on any given week there might have been 3-5 rap albums released.
Take it back to 1999 and on any given week there might have been 30-50 rap albums released.
Take it back to 2009 and on any given week there might have been 300-500 rap albums released.
Now in 2019 there's probably between 3,000-5,000 rap albums released every week.
Bottom line, there's just too much competition. People can make professional sounding albums in their bedroom with a $500 computer and a $100 mic. Back in the 80s and 90s if you wanted to make an album you really had to go to a recording studio. And when you finished the album you had to go through the process of getting it mixed down, mastered and mass produced. Unless you had some illegal drug money or a rich uncle you could make 10-12 songs, which technically constitutes and album, but if you didn't have the money to mass produce it and distribute it, you needed a record deal with a major label.
The whole paradigm is completely different. You can make an album yourself, mix and master it yourself, and distribute it yourself.
Dave East is competing with thousands of underground artists that can rap just as good as him, and their albums are just as good. The line between what a major label can do for you vs what an independent artist can do for himself is blurred.