This is what is known as “fundamentalism”. In this case, it manifests as the inability to think of Buddhism outside of a rigid, narrowly-defined set of doctrinal assumptions.
The Sautrāntikas were a specific school among the 18 schools of Indian Buddhism. Yes, they emphasized the Suttas. But that doesn’t mean that anyone who emphasizes the Suttas is a Sautrāntika. If Sautrāntika means “follower of the Suttas”, then sure, count me in. But if it means “adherent of the ancient Buddhist sect called Sautrāntika”, then no. For example, the Sautrāntikas believed that each mind-moment could be divided into two parts, arising and ceasing. I for one don’t believe there is such a thing as mind-moments, and they are certainly not taught in the Suttas. So there is some nuance here.
Early Buddhism is a perspective on Buddhism that informs understanding and supports practice. It isn’t a “sect” of any sort. A “sect” is a defined religious body or organization; compare, for example, the Thai Dhammakaya, which is indeed a schismatic sect. Early Buddhism is a loose affiliation of folks with an interest in the Suttas, that’s all.
Within this movement there is a lot of variation. But most “early Buddhists”, and certainly serious early Buddhist scholars, do not “reject” the commentaries. Rather we reject the uncritical assumption that the commentaries are always right. An authentic intellectual and spiritual life is not defined by black and white absolutes.
The Buddha never taught his followers to think in terms of attachment to group identity. He taught us to use our intelligence and understanding with compassion, to clearly distinguish what is Dhamma from what is not Dhamma, what the Buddha taught from what the Buddha didn’t teach.
To say that early Buddhism is a sect of “westerners” is racist. It excludes and silences the very many Asians who helped formulate the linguistic, historical, and practical basis on which the understanding of Early Buddhism is formed. To pick just one example, more academic work has been done in this field by Japanese scholars than the rest of the world combined. It was partly to counteract this racist ideology that in recent years I have taught courses on the Visuddhimagga, and on Jayatilleke’s Early Buddhist Theory of Knowledge, the latter of which remains probably the single most influential book on early Buddhist philosophy.
To this day, there are movements promoting early Buddhism in Thailand, Sri Lanka, India, Vietnam, Malaysia, Singapore, Taiwan, Japan, Korea, and so on. Many of these remain inside local languages and cultures, so on a superficial level it is easy to overlook them and see the international movement of early Buddhism as dominated by those who speak English.
But the reality is that human beings are human beings. And there are people all over the world who are lit with the spirit of inquiry, who urgently seek the Dhamma, and who are searching for a way to get closer to who the Buddha was and what he taught.