I don't agree with this stance.
Drake having ghost writers does not mean the vast majority of currently popular rappers are engaging in ghost writing .
All of his peers as far as I know, write their own songs and lyrics.
J. Cole takes pride in producing his records from top to bottom (not all of them but most of them..)
Kendrick Lamar takes pride in having an active hand driving the directions of his songs, even though he
isn't well versed in theory like Terrace martin or Thundercat, he's still a word smith and comes up
with the concepts and such.
Meek Mill, Wale, Lupe, B.o.B. and others all stress or have stressed that these are their lyrics
and by extension their songs.
And on much smaller scale projects dudes like Oddisee, Hopsin, Tech N9ne etc.
Handle the vast majority of the song writing duties and in Oddisee or Hopsin's case they handle
production as well !
Drake's ghost writing exposure might set a new precedent but as of right now, it's not a normal
thing at all and I think you'd agree on that.