Dedicated servers are often the holy grail among fans of online multiplayer games, but it seems that the folks at Naughty Dog specifically wanted to avoid going that route.
Via their official Twitter account, the studio had this to say:
“We’re not going to have dedicated servers, made that decision long time ago + we built the current player host-client architecture. Decision for that server architecture was to be better able to support our fans long-term if we can/want.”
“The cost delta between dedicated & non-dedicated is huge long term. Eventually someone will say it costs too great + shut them down. My personal hope is that by keeping costs down + strong enough community, we could be in a position to consider 4+ yrs of uptime.”