runescape has some of the most watered down multiplayer mechanics in any game (let alone any mmo) ive ever played
sure there's the GE and occasionally some cool pvp players if you can find a decent group but other than that your peer-to-peer exchanges usually boil down into "stop stealing my iron dickhead i need that"
shield of arrav was the most arbitrary requirement for friends and i dont know why that quest still exists
dungeoneering came out for RS3 but was honestly too little too late as you could essentially solo dungeons and when you did play it with friends you just rushed to do everything alone without their assistance, multiplayer wasnt really necessary for that skill until level 100+ when you needed someone else for the boss to attack
the game would honestly work a lot better for what it is if you could just play in a world alone