Borders offer boundaries. They keep you inside a place, a state of mind. Some people like them, others do not. In plate design, the concept has been around in a very traditional way for a long time.
They confine the food perhaps and keep the plate defined on a table.
I like the idea as part of a mix. Not exclusively, and not all the time, like so many things we do in life.
I have been experimenting with borders of late. And there certainly seem to be people who love them and others who prefer the clean infinite edge-
perhaps there is a personality study here.
In the meantime, I prefer to think of these lines, dots, blocks and abstract markings-as a new way to inform the design on the plate and capture a piece of the space that you may not have been attending to before. Encourage you to look at the plate as it stacks, nests-in a new and unlimited way.