True. But sadly, there are jealous fanbois here and elsewhere who say Truex is an average driver blessed by a magic crew chief who actually wins all those races. It is as ludicrous as saying Chad Knaus is the reason Jimmie Johnson won 83 races and seven championships. Like you said, heads (deliberately) stuck in the sand.
What you say is correct this year, with fast ovals having anemic horsepower and tons of both downforce and drag... but it was *not true* in the low downforce era... and was *not true* throughout Nascar's history (restrictor plate races excepted). One of Nascar's unique attributes has long been the very wide disparity between the performance of teammates driving comparable equipment. You don't find such wide disparity in any major roadracing series (except in MotoGP).
The best drivers win the most races... on ovals and on road courses. And as you point out, Truex is an elite driver on both (and has been for ~5 years... no fluke).