ITA.
Hot oil treatments work on the cuticles. They soften and make the outer layers of the hair pliable. They also impart a shine to the surface. Those things are nourishing to the hair-- but not moisturizing. "Moisturizing" = Hydrating and hydration is only a property of water. Hot oil treatments are basically temporary softening, smoothing, shine boosting treatments.
Deep conditioning (using a waterbased conditioner product with quarternized and hydrolized proteins and humectants + heat) will help bring moisture deeper within the strand which is why this process is much superior to hot oil treatments. Deep conditioning helps replace key ingredients and addresses the actual moisture aspect of all of this. Hair rarely thrives without regular deep conditioning, but you could go an entire lifetime without ever doing a hot oil treatment. They aren't necessary for hair health, but they are nice cosmetic treatments.