What do you mean by lyrically he hasn't progressed?

Do you determine lyrical progression by double/triple entendres and multisyllables?
If so then you've missed the point of being lyrical.
The point of lyrics are fundamentally to convey a message.
Drake is lyrical in the sense that he can successfully convey messages to his listeners that actually feel genuinely introspective; that's why so many connect with Drake's music.
I don't think there's anyone in hip-hop right now that is as lyrically introspective as Drake.