First we definitely give credit to Vitthalnathji, the second son of Vallabhacharya for completing the missing portions of Anu-Bhashya. But after that for almost a century there was no significant study of the Brahmsutra in Pushtimarg till Purushottamji decided to unearth the treasure trove and foundational principles of Shuddhadwait Brahmvaad. He assembled a group of scholars from different traditions to study the Bhashya in a comparative manner. This is manifested in his commentary called "Prakash" where he refers to the views of contemporary branches of Vedic sciences namely those promoted by the professors Shankar, Ramanuj, Bhaskar, Madhva, Vigyan Bhikshu and Shaiv. He was the first to perform such critical and comparative analysis among all the scholars of all the traditions of Vedic knowledge at the time. Therefore he was respected not only within the Pushtimarg but across all the major sampradays.
It is said that when he used to travel to places, a cart-load of books would accompany him! He is truly a pillar of the Shuddhadwait as without his herculean endeavor, we might have almost forgotten the most enlightening interpretation of the Vedic wisdom given by Vallabhacharya. Thank you so much Shree Purushottamji!