What he means is 70% of people who play would not get very far without recourse to the wiki. I partially agree. Many things are too poorly explained to be achieved, and many things too well hidden. The making of an NPC house, for example: nothing in the game explains that you need a player-crafted back wall with only small holes in it. Also, the Wall of Flesh. Many players would take forever figuring out how exactly the thing is being summoned, and would probably just stay out of Hell after getting enough Hellstone for Molten. Getting sturdy fossils, fighting Duke Fishron, getting the Tax Collector, or Happy Grenades, using functional statues, and putting together the various combo equipments, these are things that would be difficult to impossible to figure out without the internet. You have to balance the joy of discovery against stalling out or missing out because you didn't know what to do.