I phrased it weird, my bad; I meant it would enter those places (Indonesia, Cham, etc) earlier and more thoroughly, like Indonesia being closer to 100% than the current 87%. As for the issue of Theravadda, my understanding of that argument ("Transcendentalist Intransigence") is that it extends also to Christianity, Islam and Hinduism too because of intrinsic characteristics of the four; I personally don't find it very compelling because of the widespread conversions that have historically occurred, even Post-1500. I think the earlier portions of that post put it best:
Who spread Islam to the people? For one, there's the government. In some places, the mosque, the clerics in the mosque, the books in the mosque, and 40 of the people praying in the mosque would all be appointed by the state. But Sufis (Muslim mystics) might have been more important. Many Sufis had the organization to carry out elaborate plans for converting people to Islam. Sufis were also successful because they accepted pre-Islamic culture and religion, explained the complex beliefs of Islam in simple ways (like comparing Islam to a cocunut), and were seen as sorcerers with powerful magic. When Sufis died their tombs became pilgrimage sites, helping spread Islam even from the grave.
Peter Heather has argued in this way, specifically focusing in on the Christianity aspect: