No, it's not. Metro Fiber links are designed and deployed in a ring topology for exactly this reason. See:
It's really easy for a vendor to claim that there's no point at which a single backhoe can take out two of the A/B/C/D/E paths in your diagram. It's also pretty easy to buy dark fiber from two different vendors that are reselling in the same bundle or have their bundles placed in the same conduit.
>"It's also pretty easy to buy dark fiber from two different vendors that are reselling in the same bundle or have their bundles placed in the same conduit."
Wrong again. If you are purchasing an IRU on dark fiber you know exactly who owns the physical assets. If you are purchasing wavelengths from a reseller they will happily disclose whose network they are reselling. You can also easily avoid resellers and not worry at all about this.
Lastly you seem to not understand the difference between long haul and metro fiber.
It is incredibly common for multiple fiber bundles to have a shared path, because it's often easier to locate another bundle in the same place. Fiber is often laid along rail lines because rail lines have the perfect property shape for communication, and there's specialty train cars that make laying fiber alongside the rail really efficient.