The Demon Clan's Heavenly Court only gave birth to three Heavenly Dao Saints this time, a major reason being that individuals like Six-Eared Macaque were influenced by Sun Wukong, aspiring to slay the Three Corpses to merge with the Dao and become Saints, to reach the Primordial Taiji Da Luo Gold Immortal Realm like Hong Jun Daoist Ancestor. Otherwise, relying on the massive merit and destiny granted by the Heavenly Dao upon the establishment of the Demon Clan's Heavenly Court, there would have likely been more than a mere three new Heavenly Dao Saints!
By the time of the Myriad Races' return, it will truly be a world where Saints walk everywhere, and Sub-Saints are as common as stray dogs!