The article makes an interesting argument that the typical McMansion design, internally, can be distinguished by being more-or-less the same as a suburban home floor plan but inflated beyond all sense: an entry hallway turned into a grand foyer with a huge staircase (which, obviously, never actually gets used for anything, because it's still too small for actual parties), chains of special-purpose rooms stapled on to the same core set of rooms from the original nuclear family concept, access to the bedrooms stretched and stretched out as all the other spaces get bigger, etc.
It strikes me as, conceptually, a distinct contrast to an 'average' Victorian home floor plan (which is probably the other closest thing to 'mansion' that an average person might think of living in), where even a very large home is going to have pretty tight and efficient layouts meant to maximize collective practical use of the space (especially with a large family or guests), rather than just giving a ton of square footage to each individual inhabitant.
It strikes me as, conceptually, a distinct contrast to an 'average' Victorian home floor plan (which is probably the other closest thing to 'mansion' that an average person might think of living in), where even a very large home is going to have pretty tight and efficient layouts meant to maximize collective practical use of the space (especially with a large family or guests), rather than just giving a ton of square footage to each individual inhabitant.