June - Master Profiles are not necessarily famous or celebrity profiles. Further, they are not necessarily finished profiles. For many of us, they are a means to indicate a profile whose relationships (spouses, children) and data field values have been verified, and where there are errors, they have been corrected. Sometimes I add source links to the About Me at the same time as I research and make the profile the Master Profile. Often I indicate in the About Me the "vital statistics" of the individuals - marriages, children, locations lived, profession. I also give a synopisis in the Curator's Notes - usually parents, spouses, and children - if I have room. This is because when there are merges, my researched relationships and dates can get overridden or confused, so I leave myself a trail to ensure I can correct the profile a second time.
I work somewhat in the manner that Erica works. It is iterative.
I see the Master Profile as the profile that we should all merge into and work collaboratively on. I welcome all and any edits to Master Profiles, but they need to be sourced with reliable sources.
Many of the MPs I have created are early immigrants to Massachusetts and Connecticut and their families, the people who were the founders of the first towns in the United States (before the U.S. existed), such as the founders of Roxbury, Milford, Hartford, Taunton, etc.