I doubt it, but if they are it's because the community puts too much investment into 50-100-150 and now 170. They could be boosting the number to get to the maximum trade limit, which is based on total qp's It's based on the amount of quest points you have compared to the max amount of quest points. The max is always 60k until Jagex changes it again, regardless of the new quests being released and more quest points being obtained. But perhaps Jagex feels the current max qp is not worth a trade limit raise? So they're releasing more quests until they reach a point where they think 100k etc... is reasonable.