The Diamond tables have a leveling system designed so that level adjustments, even seam adjustments, can be made at anytime with the table fully assembled. You definitely need to glue the seams together in order to make these adjustments or you would loose the seam. Secondly, wood is affected by moisture and temperatures, earthquake, houses slowly sliding down hills, people leaning on tables. These are all things that make tables move. It nice to have the slates glue together so you don't have to remove the cloth because you lost the seam alignment when releveling these tables.