Why would anybody waste valuable resources going on a dangerous journey all for the sake of revenge? Ellie in TLOU1 mentioned to Joel how he had "plenty of food in his time" which of course implies that there is widespread famine in their current time. Wouldn't people be focusing on survival above all else?
Even if they did have extra resources lying around, why would they risk their lives going up against bandits, dangerous cults and the infected all strewn across the country? They don't even know where Joel is and if he's still alive. On top of that plenty of people have already died during the outbreak. Are they going to all go on a revenge journey every time somebody they know gets killed by a bandit, which would be often in the world they're living in?
25+ years of gaming taught me one important life lesson. You normally have to create an alt to defend No Man's Sky.