Personally I do not believe it to be good practice. My opinions only come from personal experience and unorganized research. I have not found an authoritative explanation as most authors take the matter for granted.
My understanding of the theory is that any ESD from the connector or otherwise will travel through the chassis ground ring to the chassis connections and earth ground. The ESD is supposed to see this path as low impedance compared to the single point of entry at the ferrite or inductor that protects digital ground. I have no problem with this theory like that.
However, in your layout, the ground ring is very small which as others have mentioned, appears a non-zero impedance. So if you do want to use this grounding topology, then I would widen the chassis ground loop trace.
The above theory has limitations though. What happens when I want more connectors than just USB? Look at a PC or laptop motherboard with many peripherals. For each of these you would need to a clear path to chassis ground for any ESD. Some designers decide to add ferrites at each of these entry points to maintain that high impedance but keep the same DC ground needed for operation.
Also consider what happens if I connect an off board device such as a hard drive or touch screen. Now I have to make sure that the peripheral is using my ESD protection architecture. If for example the touch screen uses a unified ground theory, then any ESD coming through the touch screen will find its way to my motherboard's digital ground. Couple that with the fact that my motherboard has high impedance ferrites blocking the exits to chassis/earth ground and now my components have to soak up all the excess energy from the ESD event.
This is why I do not believe that this isolated ground theory (also known as star ground) is scalable. It's ok for small sections like an analog critical area, but is difficult to maintain through a large system.
The alternative is a unified ground theory. Treat all grounds where possible the same. To reduce the impedance between different parts of ground, try using planes (voltage and ground), thick copper, many vias and generous mounting holes. If done right, there should be no useful ground loops. Combined with sufficient board capacitance (the right kind too), power rails and signals should be able to float right over the ESD event. The majority of ESD should find it's way straight to earth. Or in essence, we are applying localized single ground theory.