Brownies are so very rarely made from scratch. As with mayonnaise or marshmallows, the idea of starting from the beginning is simply obsolete. Homemade brownies, the kind you make without the box, may well be on their way to extinction.
I have two theories. One is that people are of the delusional thinking that brownies are difficult to make, which they are not. Basically you melt some butter and chocolate, add eggs, maybe vanilla, a heap of flour, stir, pour and bake. It's right up there with boiling pasta. Making cookies is slightly harder.
The second theory is that people believe that brownies baked from scratch will be no better than those made from a mix. We settle for "pretty good," as my friend described his from-the-boxers, because it seems impossible to make a brownie that tastes as good as those costing in the neighborhood of $2 in a decent bakery. But, as someone who spent a summer baking sheetpan after sheetpan of serious chocolate brownies in one such bakery, I am here to tell you that there is no secret. But there is one consideration that outranks the rest. Baking time. Those brownies you see stacked so high and chocolate-mighty in bakeries are gooey and rich not because the chocolate in them is worth its weight in gold (though the better the chocolate, the better the brownie). And not because they were baked in a special oven, or by someone with lofty training. Those brownies were simply baked for just the right amount of time. Maybe less.