Shannon, as Adrian said this is an excellent question, but we have to think about the geometry of the earth. Standing on what appears to be a flat plane, the horizon is about 2 1/2 miles away in all directions. Since within that "buffer" distance the curvature of the earth is not relevant to distance or area calculations, a geodesic distance or area would not be appreciably different than a planar distance or area, depending on the projected coordinate system applied.
In addition, when a surveyor is working on a project, collecting measurements for lots in a new subdivision, or an engineering firm is working on a road project, collecting distances in degrees in not really practical.
The other issue is that a degree on the ground at the equator or north-south, is approximately 69.2 miles or 111 kilometers. A degree of Longitude on the other hand is variable depending on the distance from the Equator. Using the calculator at the link below, you can check the length of a degree of Latitude in comparison with the length of a degree of Longitude at a specific north or south Latitude location.
http://www.csgnetwork.com/degreelenllavcalc.html
In order to maintain maximum accuracy in coordinates in decimal degrees, you would have to capture the coordinates out to more than 11 places to the right of the decimal. With a projected coordinate system you can obtain distances and areas to centimeter or inch level.
You might want to check out Esri Knowledge article 000006113 at the link below. The article includes information about the properties of projections, and includes a link to a list of supported map projections and their properties in Esri software.
https://support.esri.com/en/technical-article/000006113
