It's things like this that really make me wonder what goes through the minds of JWs these days. How do they justify it to themselves? To my mind, at one time, JW beliefs were at least plausible. And if you wanted to find problems with JW doctrine, such as 607 BCE, you had to specifically go looking for them. At least the doctrinal system was in itself coherent, even if it lacked outside evidence or support.
But with the overlapping generation, and increasing partakers, the inconsistencies are right out in the open.
The typical JW reaction seems to be just to avoid talking about these issues. That doesn't seem normal. Most JWs must know something's not right. I just find it weird.