Kemp is ridiculous and obnoxious. He literally aired ads about his truck.
Running vapid ads about your truck never works.
https://youtu.be/nnZw6sm_yAY
As far as being "ridiculous and obnoxious" vs "talking about the issues", I can think of a very recent high profile election where that was the case, and it didn't turn out very well for us, in Georgia or otherwise.
Notice how Scott Brown talked about ISSUES in that ad about his truck. Brian Kemp was just talking about what a gun toting rural rube he is.
YUGE difference.
We are living in different times and talking about different states too. Kemp talking about his truck, guns, and barbecue (?) or whatever may very well be enough for modern Republicans to make him their Governor.