Well one thing about complaints on the internet is that alot of people like to complain. IMO internet reviews aren't always balanced.

If you're overly concerned about gnats then go ahead and bake it. But I assume they're going to be outdoors anyways so you probably don't need to.

Baking any soil will result in a stench that you will not like that can last for a fairly long time. Many potting soils will have the eggs that can hatch into these Fungus Gnats, if the soil is kept too moist, too long. To keep Fungus Gnats from hatching out water only as necessary so the top inch is kept fairly dry most of the time. Water the plants growing in this soil only when the soil is dry after you insert your index finger in to the first knuckle.