It's not a myth; high fat is a great diet for many and works well depending on your goals. However, I would suggest that if you are doing anything that requires v. high caloric intake and/or sustained performance/weight gain that at least moderate carbs are the way to go.
The basis of Dr Sears et al. is hyperinsulinemia, which is very real and is serious. I would not suggest you eschew fat altogether; only that going v. low carb / high fat, given your goals and reactions, may not be right for you. That doesn't mean ditch the fat or eat a bunch of pasta, only that you should moderate your macro ratios and total calories in a manner that is more in line with what you're trying to do and how your body is reacting.
"Use what talents you possess: the woods would be very silent if no birds sang there except those that sang best." —Henry Van Dyke