Presumably, everyone present knows that the game truly begins at max level.
When leveling up, there's no time to go around doing quests, but once your combat power is maxed out, you have to farm materials, equipment, entries, mounts, reputation, achievements, and join group dungeons to earn DKP, there's just too much to do, you can't finish it all!
The same principle applies to people in the Mystic Sect, Nascent Soul True Man is just the entry point, if your level isn't maxed, skills aren't fully unlocked, who would accept you into the core circle for group dungeons?
To put it plainly, before forming a Nascent Soul, the thresholds you can pass relying on natural talent, Daoist Heart, and Immortal Fate, others can't help you much, you have to rely on yourself. After forming a Nascent Soul, facing the unsolvable problem of resource scarcity, no one can help you either, everyone's stuck at resources.