Jagex made a new play style in their game Runescape. The style is called Ironman. On the page describing Ironamn, they specifically state that there will be a no trading restriction put on Ironman characters. The whole mode is about doing all the work yourself.
When you buy the subscription and start playing in Ironman mode, you soon discover that the no trade thing was a complete lie and that you still have to team up with another player and trade with them to complete two different quests.
Those quests lead to other quests that can not be done without first completing the aforementioned two quests. Those two quests and the quest lines that they are involved in open up areas of the game and allow you to use certain weapons or armor in the game. Some of the later quests also let you use spelss and other things that are not obtainable without first taking part in the two quests and having to team up and tade with other players.