It's not "just" PG, it's like a mega-extension with data-types and tuple-layout and a tonne of magic for the data-domain. You can, of course, make similar mode

It's not "just" PG, it's like a mega-extension with data-types and tuple-layout and a tonne of magic for the data-domain. You can, of course, make similar models with plain PG - in the same way one does GIS without PostGIS.