The official way to measure was asked about and the answer has been there as a standard for many years. I would hope our goal in this sport is consistency of procedures for fundamental elements such as the way we use feet instead of meters for hole length at least in the U.S. Both the Course Designers group and the PDGA have converged on the measurement process based on following the fairway like ball golf but in rare cases taking into account direct power routes when that occurs.
Here are a few mental exercises to consider. We have a square barn 150 feet on a side with a tee at one corner and pin at the other. You cannot throw over it. Should the hole length be 212 feet measuring as the crow flies (diagonally through the barn) or 300 feet going around the barn? You're driving in a town with the common rectangular grid pattern for roads. Does your GPS give your distance as the crow flies between two points diagonally across town or the actual distance that would show up on your odometer?
We have a rectangular pond 500 feet by 200 feet with tee and pin diagonally across it each 20 feet from each corner. No one can throw that crow flies 578 feet from tee to pin. How should you measure the hole distance, presumably as a gold level tee? Let's say Gold level can safely throw 300 in most conditions. (It doesn't mean they can't throw farther, but that's their "safe" minimum for crossing water with enough clearance). This type of hole would likely be gold level so you measure to where their typical landing zone would be diagonally cutting across the corner of the pond at the 300 ft point along the bank then straight line to the pin.
That's the same way they would measure it in ball golf if the pond was those dimensions in yards instead of feet. It's a virtual dogleg created by the driving distance for the skill level the tee was created for in both BG and DG.
Bottom line: Follow Flyable Fairway