And we can still spread out from there. It is a well-thought out element of the Hyperion Cantos (occult SciFi): They do have some kind of Stargate to insta-travel, but building those Stargates requires people to travel for decades if not hundreds of years. These guys are put into stasis for the duration of the trip, and get to go home every couple of decades to talk to their grandchildren/distant descendants.

Leaving SciFi aside, our communication technology will be up to the task of relaying information comparatively quickly (light speed or faster), and parallel societies could be built in neighboring solar systems.