It is a myth. Usually perpetuated by people who have never stayed there.
The distance and time is comparable to OKW and SSR from the parks. 10 minutes max to AK, 15-20 minutes to MK, Epcot or DHS.
The big difference is that OKW and SSR have several in-resort bus stops. AKV/AKL have just 2 stops.
The Epcot
DVC resort buses stop at BC/YC, BWV, Swan and Dolphin.
Even BLT requires walking over to the CR to catch the monorail and then transfering (up and down 2 ramps) at TTC to go to Epcot.
I will say that the trip from AKV/AKL to Downtown Disney can be a bit time consuming depending on the time of day and traffic. Allow a good 25 minutes or more to go. On the way home in the evenings, if all the parks are around closing, it can take 30-40 minutes to get back from DTD in all that traffic.
The buses to/from the parks pick up at Kidani first, then Jambo. The buses to/from DTD pick up first at Jambo, then Kidani. Peak times of day may require people at the second stop to have to stand on the bus. If you are at Jambo and want to go to Kidani, it is a 10 minute walk. Or you can hop on the DTD bus and ride it to Kidani. Same in reverse. If you are at Kidani, you can walk to Jambo for the CS restaurant or hop on any park bus and disembark at Jambo.
The resort is now using a combo of golf carts and a passenger van to also run guests back and forth to the other side of the resort. Just ask the valet at the doors if the van/cart is there. If not, they will call for it and let you know how long it will take to arrive. If the weather is fine, again, it's just a 10 minute walk from door to door.