LogFAQs > #971253264

there is plenty of environmental storytelling, journals/notes, and stuff like that.

the brutality of the gameplay relays both how violent the world is, and the scavenging to show it's a dying world (as far as humans go), that the player has to rely on things made in the past to survive.

people have argued that the infection is a metaphor for Joel's loss of humanity.

so, everything that you experience is meant to add to the world, feeling, experience of TLoU, and not as some secondary thing that has a minor purpose.