That used to be the case, but now a "brick and mortar storefront" is a de-facto requirement, the Clinton Administration having aggressively ended "kitchen table gun dealers" and reduced the total number of dealers by some 75% nationally. The only practical exceptions are "gun show vendors".
ETA: other dealers do exist, yes, but nowhere close to the numbers of some years ago, and not to the point of making "the title totally misleading".
ETA: other dealers do exist, yes, but nowhere close to the numbers of some years ago, and not to the point of making "the title totally misleading".