Shaykh Muqbil (Rahimahullaah) was asked this question and he said:

“The reason was by distinguishing (ourselves), we distinguished ourselves from the people of bid’ah and therefore Allah had spread the sunnah. He also gave an example of how a person of innovation would come to the masjid in order to speak and everyone would leave, meaning they made Hajr (seperation) from him and humiliated him. It was my brothers who distingished between ahlus sunnah and ahlul bid’aa, that was a great reason for the spread of the da’wah. While blending and mixing with ahlul bid’aa has the opposite affect (allowing innovation to widespread).”

The Methodology of Ahlus-Sunnah wal-Jamaa’ah in Warning Against Innovators and Their Books Author: Shaikh Rabee’ bin Haadee al-Madkhalee

Source: book Manhaj Ahl-us-Sunnah wal-Jamaa’ah Fee Naqd-ir-Rijaal wal-Kutub wat-Tawaa’if Article ID : BDH050002 [19575]