I’m not even sure if you played the game
The online intersection allow you to avoid doing the endless travels to get material to build a bridge or highway.
The key passages on rain will have some shelter or energy supply playing online… so you don’t need build them and have several travels to do that.
At bosses people help you with weapon and support cargos.
You have always some transport near you so you don’t need waste time going to base to get one.
You have several fast travel builds near you so you don’t need to waste your time.
It is basically a live game that helps you on the boring tasks.