Possibly, I can shed some light, having grown up in that era.
Public talks were not limited to elders. Qualified speakers who were at least 18 years of age were assigned such talks. Since I was already pioneering and the P.O. forgot to check my age, I gave nearly 50 talks before I was 18, as many as three on a Sunday given the staggered meeting times.
I was appointed as a Congregation Servant at the age of 21. That was the pre-elder equivilent to Presiding Overseer. I was also department head at the circuit level. I began giving funeral talks at the age of 19.
Part of what I've just stated above leads to jealousy and back-stabbing. During my youth, I experienced the same political manuevering by elders older than myself who were jealous of my opportunities. It takes several of these situations to get battle-hardened enough to protect yourself.
Unfortunately, I can identify with what Miller said about non-white elders flexing there muscles a bit after being appointed. I was foolish enough at one point to allow myself to be appointed Presiding Overseer in an otherwise all-black congregation. Without giving details, we barely got out with our Theocratic lives.
I can identify with much of what Miller states. The story may not be totally objective, but the basic details fit with my life experience.
tms