So sales get diffused among more disks. Which is what I just said only with much fancier words. What has worked in the past may not necessarily work in the future. Blindly following the methods of the past will result in frustration. The scale is smaller, the time frame for release is shorter, the percentage of money returned to the artist is higher.
Advertising is small or non-existent.
In a small operation you have nearly complete control over most aspects of what you are doing. The act of music is not merely the sounds on the record, it includes how those sounds are transmitted to the world. Major labels, in my current opinion, are not nearly as evil or short-sighted as they used to be. Some areas of culture, should you wish to get involved with those areas, can only be accessed through major label involvement. Those channels of media, distribution and retail are pretty rigidly controlled.