DZ is basically all ive been doing lately and it can be toxic AF. At the very least you should be able to transfer servers without what they consider a "Bad Connection"as all connections in the Division are Bad Connections. Some servers are great and i can have fun for hours while other are just filled with trash lag and Cronus users, like tonight and its always the ones who are skipping around the board or using cronus that talk the most crap.
What makes the dark zone the "dark zone" is that PVP can occur. Without PVP, the DZ is just a better LZ without missions.
That being said, I cannot say the DZ promotes bullying but I think I know why you believe it to be. It is this: PVP act as a gradient in the DZ, in my opinion. No one really knows when it starts or when it'll end. It doesn't happen all the time and it's not a mandatory thing that everyone needs to do, but it can happen in the DZ. Overall, I believe PVP and DZ are two different things.
I think PVP and how it is handled is the problem rather than the DZ itself because if PVP was disabled, I don't you would've had this experience, for obvious reasons.