Neither it is necessary to adopt the wasilah (intermediation) of saintly elders in duas nor Almighty Allah needs it. He accepts our duas without wasilah as well. However, it is known by hadith that a dua made with the intermediation of pious elders or good deeds is accepted more quickly. There is a famous hadith in Bukhari named Hadith Zarir in which the holy Prophet Muhammad (صلى الله عليه وسلم) taught a sahabi to make dua through wasilah. It is also proved to supplicate with the wasilah of Hadhrat Abbas (رضى الله عنه).
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband