Because he was a special gopi serving Radha and Krsna conjugal. That is why he could give this thing. So Rupa Gosvami is the topmost servant of his Gurudeva. If anyone can serve his Gurudeva to establish the same mission in the world, then he is the topmost servant of his Gurudeva…
If that greed is not coming, then their life is bogus. They should go to the Ramanuja, Sri sampradaya or any other sampradaya. This is the speciality of Caitanya Mahaprabhu, that He has not come to give only vaidhi-bhakti. He came to give and sow a seed in the heart of devotees. What seed? Krsna-seva-vasana, the desire to serve Radha-Krsna conjugal…