Meandrogrog
LemonJam
Countries don't 'need' borders because country borders already exist.
The issue is how countries and their allies decide how to control and manage their borders.
A country is broken if it cannot control its borders.
Well, no country CAN control its borders. If it's a vast country like USA, its borders with Mexico and Canada are so huge they will always leak.
A not-huge island like Britain or Ireland has a huge coastline, most of it unoccupied and unobserved , where boats can land.
In Africa, Europe etc every country borders many others and anyone on two feet can walk across borders at night unseen.
None of this is new, humans have been migrating for ever.