Because they offer the best risk/reward opportunities. Especially with breakouts, once prices have left the previous level of support and resistance, they will travel until they find a new area of consolidation. That “trip” is the trade you want to wait for. That trip is often the beginning of a trend. And discretionary trend traders are legendary for having been able to reap outsized returns relative to the risk taken (Market Wizards, by Jack Schwager is a must read).
However, trend traders are falling out of style. Every edge or discernible trading pattern is being exploited by sophisticated algorithms, making those old principles more difficult to abide by. So far, in my brief trading career, it seems that the only way to avoid the “gyrations” or “shaking out” around support and resistance levels is to allow for wider stops with smaller positions and give the security time to find its new groove and head to its next destination.
It is also in these moments of indecision that it is valuable to have a big view of the fundamentals behind the commodities being traded. The supply and demand and the global economic factors driving the physical movement of a particular commodity, can give you some insight in what trade you will take when support or resistance are in the way. Other traders see this as a detriment to one’s ability to execute what the market is telling us already through the price. I think there is some truth to that. They key is in giving the proper weight to fundamental information and if there is a big disconnect between fundamentals and price action, always follow the price. Don’t let your opinions about the economics of a commodity stand in the way of what the market thinks!