A much smaller number of players are producing surplus quantities of those valuable goods and providing them to other players. And all the gold generated by the activities of those players who ignore the grindy professions and get what they need from the auction house is flowing to the players who are making all those goods available on demand to the rest of the community. Most of these auction house merchants are sitting on a lot of gold, but the number of people who want to make cash this way is relatively low.
Make sure you have the two Flight-Path toys purchased, as this can save you time. It won't have EVERY flight path, but will have major locations for faster travel if you need to switch zones entirely(which you will). If you buy the toys on one faction, it unlocks for the other faction as well. So don't spend double the gold! These toys can be found at the heirloom vendor(Undercity for Horde, Ironforge for Alliance)
5% was admittedly an exaggeration, just felt that low. I'd say it was probably closer to the 30-40% range. It was Artifacts of the Blacksilt, spent a good 10-15 minutes killing Blacksilt Seers to get two damn idols to drop. A quest that had me killing Elder Brown Bears for bear flanks also took quite a while, though that was less due to drop rate and more due to how spread out they were.
I found that in most cases, I could pick the zones I liked and skip everything else. It was slower, but I still wasn't forced to do quest zones I hated (and, notably, I skipped the entire Cataclysm expansion's content -- sorry, Thrall.) I did do dungeons, both in group finder and by two-boxing (more on that in a moment as well), but only once for the quests, and mostly to clear what felt like an awfully long slog from 40 to level 80.
In Legion, some of the dungeons include the Black Rook Hold, a max-level dungeon in Val’Sharah that once served as an elven fortress but has been corrupted by a malevolent force. If you decide to quest in Stormheim, you can also try to clear the Halls of Valor, which lets you take on the Vrykul God-King and vanquish the pure Val’kyr that are superior to those found in Northrend.
Something to keep in mind as well is that this will make enchanting materials more valuable, since it is likely most players will now simply scrap their boe greens instead of getting them disenchanted. Also redundant dungeon/raid gear can be scrapped rather than traded to the (guild) enchanter in the run. Less stuff gets disenchanted, meaning there will be less ecnhanting materials, meaning their value will rise. All the more reason to DE rather than scrap as an ecnhanter.