I generally agree with your last sentence, but maybe it's a mistake to generalize it to other activities or professions.
If an adequate surgeon has an 85% success rate, and a brilliant one a 90% success rate, then it's arguable that being ten times smarter or more dexterous isn't that important, to be overly rewarded. So in that sense, merit might not matter.
But many activities or professions lend themselves to multiplying others' results. What if someone can teach all the surgeons to have 5% fewer failures? That still has diminishing returns, but what if someone figures out a way to do, say, twice as many surgeries with the same resources, or to eliminate the need for half of them? You might say they still don't need or deserve wealth, but in order to reap the benefits, society has to give those people power in some form to organize the activities of others. And wealth tends to flow to those with power.