Is it possible following the principle of the Chinese theory of acupuncture to have beneficial effects without the needles?
Sure! In fact, the ‘theory of acupuncture’ is actually the theory or principles of Chinese Medicine applied to the modality known as acupuncture…. In other words, Chinese Medicine is an entire medical system (the only one the Chinese had for thousands of years) with many different modalities. One happens to be acupuncture. Some others are: herbology, cupping, tuina (meridian massage), qigong (medical exercise), moxa therapy (heat therapy via application of the burned herb moxa), and dietary therapy.
So, if there were a reason not to use needles or you didn’t want to for whatever reason: no problem! The theory of Chinese Medicine overarches and informs every treatment modality; so your acupuncturist, to the degree of his/her training, can simply apply another one or more. In my own practice, I often use several, either formally or incidentally as the need arises.