Sometimes, one element can substitute for another. Chlorophyll contains a central Mg2+ ion surrounded by a porphyrin (above) yet runs at about 70 % efficiency when a Zn2+ ion replaces a magnesium cation. Mg2+ and Zn2+ resemble each other and since the cation isn't doing anything exclusive to magnesium, perhaps this is not surprising. The simple role of native magnesium in chlorophyll is to polarize the electrons in the surrounding molecular scaffold.
Hollywood and Washington D.C. are like the porphyrin scaffold in chlorophyll. A more or less permanent structure surrounds a central star and or an elected official. Most any organizational structure is like that. The surrounding scaffold comprises pundits, critics, enablers, staff, etc., and nurtures but eventually disposes of central atoms for the next one.