There are more passive methods to gain wow classic gold, but these are slower. For example, many people choose to fish in places like Tanaris, or kill Harpies in Feralas and loot items such as mageweaves. These are rather AFK-able, but again, not as rewarding. Some people choose to favour fun over anything, and like in any MMO (massively multiplayer online game), the best way to have fun is playing games with friends or your guild. Dungeon runs with your friends provide social interaction and are definitely helpful over the long-term for your gold stack!
To fully understand the interplay, consider terrain. This includes the placement of hills and valleys, trees, buildings, and more. When hooking up the old terrain data files to the new modern game system we realized that the way the system looked at the shape of data was different. This resulted in the updated system and classic data not aligning, resulting in weird issues like Kolkar campfires underwater or burnt-out trees from the Cataclysm era appearing in the original world.