I get the point of the article as it chooses to phrase the problem - and very interesting too.
But that's too narrow a definition of "resources", just to talk about elements or even compounds. Here are some resources of special interest to me, as hobby of stone carving and jewellery.
Spoiler alert: if your only definition of value is to weigh the stuff, then yes we have plenty. But for much of the real world, that rather misses the point.
Blue John fluorite. Only two sources known: classic Derbyshire mine is finished. There is NO MORE. Fragments, but if you want to carve a small bowl like those that were done a century back, you are out of luck. There is a Chinese mine, and it is nice, but just not the same - not as veined and decorative.
Alabaster. The largest and best quality mines are all mined out. You can still get good quality stuff, but only relatively small chunks now. "The ancients" had access to fault-free chunks at multi cubic meter sizes, and there are existing sculptures to prove it. Now, at whatever price, to get a single fault free cubic meter is no longer possible. There just aren't any left.
Marble - not as extreme as alabaster, but we are starting to suck the dregs on top quality vast chunks. Kitchen work tops, fine. If you wanted to carve Michelangelo's Slaves out of top quality Carrara, tough. You live three centuries too late, you missed your chance.
Diamonds. These are plentiful, made rare only by monopoly. But if you want a flawless 1000+ carat, the last of those was found in 1905 (cullinan). Despite the total diamond mining throughput being orders of magnitude greater now, the goodput of vast diamonds dropped through the floor nearly a century ago.
Good quality nephrite jade. Hundreds of tonnes plentifully available still mined. But by comparison to classic sources, small and flawed. Only useful for tiny dragons now.
Emeralds. Modern emeralds of significant size AT ANY PRICE are basically shitty, flawed and with lousy colour. I have some old photos of my grandmothers emerald necklace. Central stone 30 carat flawlesst, plus another 20 carats in medium size stones. Today - that would buy palaces. Then, a middle class woman could wear it on an evening out.