Yes, it is a separate (TB3; Alpine Ridge) controller. Of course . . . and it is just a choice . . . the weight of the device is 2.7lbs instead of 2.03.
I know I would like TB3 on a Macbook because I would like to drive a 5k display at 60hz. Is that what most people want TB3 for on this device? Or are more people looking for a dock solution that has more throughput than USB at 5Gb/s can provide? Because a middle option enhancement that Apple could theoretically make with little change in 2018, relatively, and assuming Intel bumps up the cpu lane count in Amber Lake . . .is to move it to USB at 10Gb/s (Gen 2). This might help those of you who need more throughput in a certain way, however I am not aware of any USB monitor that can output 5k at 60hz so it would not really address my need.