Many singers and rappers usually begin by writing their own music, but then they stop after they get well-known and famous due to being too busy. Instead, they hire someone else to write their own music. At times, you may see on an album that some famous people may have written a song for another famous person. Also, sometimes, you will see that one or two songs on an album were written by the musician, but the others were not.
For Drake, there is some speculation that he did not write his own lyrics. Others including family members of his may have written is own lyrics. It is difficult to believe that high-paid celebrities who are touring and incredibly busy still write their own lyrics.