I think that's a good explanation H and some historians agree.
It isn't just the concept of the Trinity, it is the entire Hellenization of Christianity that took place in roughly the 2nd Century and became the dominant model until around the 8th Century. Judaic Christianity, which was a mix of the early church, Judaism, and gnosticism, was still a dominant form of Christianity in the Middle East. Moreover, these Christians never had the Graeco-Roman urge to place logic, order, and law into every corner of the faith. They still held mysticism in high regard.
Therefore there wasn't a strong desire to understand that 3 = 1. Whereas, for Augustine, it required a higher form of Trinitarian mathematics. So there is this idea, which has been offered by Christian historical scholars as well, that Islam not only offered the formula of one God (1=1) but also strenuously pushed the idea that there is only one God. It was simpler and like Judaism, Islamic Laws were concerned with day-to-day living and not higher principles of theology.
In other words, Orthopraxy was stressed, not Orthodoxy.