I'd have to have someone show me a brisket that was done when it hit 180 degrees while being cooked at a chamber temp of 250, especially in 6 or so hours. The numbers just don't add up. Before anyone jumps up and down, it's definitely possible for a brisket to be done when it hits 180, but it takes a lower chamber temp and a real long time for it to finish. Basically, it's like doing a sous vide.
The reasoning is that for brisket to be nice and tender, you have to break down the connective tissues between the muscle fibers. These tissues start to break down at 140ish degrees, but it's a function of time at temp, or temperature over time. The lower the chamber temp, the longer it takes, conversely, the higher the chamber temp, the faster it happens. During a normal cook, the tissues will start breaking down slowly after the IT of the brisket reaches 140. As the temp goes to 150, the breakdown accelerates a bit. Same when rising to 160, 170, 180, 190, yada, yada, yada.
One exception to this would be a somewhat fast braise where you partially submerge the meat in liquid then cover or wrap in foil. But, the resulting texture and flavor here is more like pot roast than brisket.