Portals have been in use since 4th edition and are even more in use in 5th edition and I doubt Larian is going to change that.
Arcane Gate, which is the closest ‘portal’ spell is 6th level and lasts for ten minutes, is concentration and only has a 500’ range. So while there is precedent in recent D&D for portals, having permanent ones is incredibly rare. Having a network of portals you can access from anywhere all clustered together in one region? Totally unheard of. Feel free to prove me wrong though.
Teleportation circles would be more appropriate, but even having them clustered so closely would be very strange. And you’d need to cast the spell or use some kind of item to access them (neither of which you need to do in this game).
