I'm not saying your method won't work. It obviously does and has been done that way since Moses seeded his yard back in Jerusalem.
It's just old school, labor intensive and you're sortof limited in the size of properties you can handle. Kudos for finding machines that make life easier for your method though. I am all for that and do the same thing.
Any excess thatch that comes up is coming up for a reason, and can be spread out with a blower which is what I do, or raked lightly and left in containers at the clients curb.
That is most certainly insect damage Rick. The fact that you have a thatch problem on the lawn or any lawns backs that up too. Chinch and sod webworm target thatchy lawns iMO.
At the end of the day that lawn looks very nice. Good job.