This is true, but many DMs get lost in the balance of it all. The point of the coins is to make the objects d’art even cooler than they are. The contrast with the more mundane stuff is critical to the effect. It’s why even 14-course meals for aristocracy served a soup and salad; why the more attractive often hit the nightlife with a pack of plainer-looking friends; why the artifacts section of the DMG would not have worked nearly as brilliantly if the entire magic section was similarly crafted.
You have to have unsexy, absolutely utilitarian, functional rewards as the standard or the dopamine does not flow in the way it should. Juicing works for a little while; then it all starts to look the same. And the brain doesn't understand when to drip the next hit like you’d expect.
I’ve been in campaigns like this. “Oh, another find of six gems and no coin”, or, “the priceless statuette of Mahringa-Mua”. First time is great. Then it starts becoming a hassle when every trip to town has a mandatory liquidation session where conversion into coin is necessary anyway just to cover overhead expenses. And it’s the priceless statuette of Mahringa-Mua - the DM can’t just exchange that at the money changers because then half the effect is wasted. At that point everyone’s in for a penny, so we’re in for the pound and it becomes The Hunt For The Buyer of Mahringa-Mua
Meanwhile, we’re stuck with something we can’t use to pay the mercs, train, exchange 1:1 without a huge loss for the remove curse Joey Two-Toes needs after taking the statuette of Mahringa-Mua off its pedestal, or buy a beer.
This is why one persistent quibble I have with the new OSR is the disdain for “mundane magic and treasure”. You don’t get OMG magic and treasure unless it’s contrasted with utterly utilitarian, boring, vanilla magic and treasure.
Then the eyes light up
While your average Hollywood Star looks utterly bored with whatever 10s on their arm, today.
My rule of thumb is that if the party needs to sell the gems and statuette of Mahringa-Mua for expenses instead of keeping it as an awesome trophy in their stronghold, then I’m not giving out enough boring precious metals.
Don’t worry about the XP - that’s why level drainers are in the game. Chutes and ladders doesn’t hurt so bad if the game doesn’t make you move only 1 or 2 spaces on your turn so that it lasts longer