Are carbs essential for weight training, imho yes I do believe they are. ATP drives muscle contractions and since the amount of ATP in the muscle is very limited (enough for only a couple seconds of intense muscle activity), it must be continuously supplied through both anaerobic and aerobic pathways. There are 2 anaerobic pathways: the phosphagen and glycotic pathways. These 2 pathways provide immediate ATP in limited amounts BUT are critical for high intensity, short duration exercise. The aerobic pathway is necessary for sustained energy. It's far more efficient than the anaerobic , BUT it cannot produce ATP rapidly. It provides energy for low to moderate intensity exercise by using carbs, fats, and protein as fuel.
I feel if you're training for strength you do need carbs in your diet but they should be timed right.