If this doctrine and Orthodox cannot even attain True Immortals, then it means that it cannot aid in Cultivation, and one cannot certify as a True Immortal. It will immediately face the rejection and abandonment of all Cultivators and can't possibly gain support.
Therefore, although the doctrines in the world can be described as "a hundred schools of thought contending," the ones that truly possess a Tao-Certifying True Immortal existence are only a little more than a hundred. Among these, dozens of doctrine lineages, despite having True Immortal Strong, their attainment of True Immortality is often a matter of chance, which they themselves cannot explain. At least until a second Tao-Certifying True Immortal emerges, they are destined to not thrive any further.