These are two holes I cut by using bool tool, my question is why the edges 1,2,3 are necessary, I have a rough idea that all the shape needs to be at least N-gons, so if there is a standalong hole without any connection to the mesh, it is not allowed, but why should we follow this rule, in other words,
1.why the feature is designed in such way, is this reasonable or not, I think this question will help me better understand the mesh, so thanks in advance!
2.Is edge 1,2,3 has to be at the same location as shown on the screen shot? Can the edge 1 replaced by edge a?