There is some truth to this, but it is not the whole story. I have crossed paths with MANY software people with lots of experience who just don't think logically. They write spaghetti code, don't know how to methodically test, and basically come in shotgun blasting to try to fix bugs and usually make more bugs. I have worked in Silicon Valley and it was no different, in some cases worse. Companies were so desperate for "talent" they would hire anyone with a pulse and a software correspondence course. It has been good job security for me.
In running, like engineering, there is a talent component. Some people have great form / efficiency without trying. Some people respond to training stimulus almost immediately. Some are slower but make significant long term adaptions. Those with less talent (bad form, poor adaption) can work harder and get better. That works to a certain level. However, when you move up in level (D1, national class, international class runners), it basically comes back to talent because everyone is working hard. That kid who gutted his way to 4:23 in HS running 75mi/wk often doesn't make the cut. The kid who ran 4:23 in HS off 20mi/wk might make it. Who has "more total effort placed into their craft"?
To the original post - Capillaries get built by consistent aerobic exercise, as much at high aerobic as possible. Read books by the best: Lydiard, Daniels, etc. They all emphasize high aerobic efforts.