I just randomly came back to this topic, which raises a range of interesting questions.
He most certainly is not. So far as I know, Schopen has literally never been to India or set foot on an archeological dig[*], nor has he any qualifications in the field. He’s interested in archeology to the extent that he can use it to discredit experts on early Buddhism with whom he disagrees.
Having said which, I don’t believe that the Jivakambaravana, nor at any other site, dates back to the Buddha. Maybe it’s an early pre-Ashokan complex, but even that is tenuous.
Oh well, let me oblige!
In the passage you helpfully provide, we find a typical Schopenism. He addresses the fact that one of the reasons the Jivakambavana is regarded as early is that there are no stupas, which are almost always found in later monasteries. But Schopen argues:
There are, in fact, a number of other “Elliptical Structures” similar to the Jivamabavana, and … at least two of them “are identified as stupas”!
For Schopen, it’s quite exciting that he can prove someone else wrong. The problem, though, is that a glance at the “elliptical structures” of the Jivakambavana shows that they are nothing like stupas at all. If he had seen them he would know this.
(Just to be clear, what you are seeing here is a modern reconstruction of the old remains. When excavating, archeologists will uncover the remains, then use the old stones or bricks around to cover the old work so that it doesn’t erode or get destroyed by tourists. I was recently at an ongoing archeological dig in northern Sri Lanka, where they were studying and protecting a nearly 2000 year-old monastic complex in this way.)
And I wanted to circle back to this quote from Wynne in the OP, after the (non-exhaustive) range of evidence provided by subsequent posters:
Ārāma in this kind of context describes a regular residence for monastics, supporting a large, established community with a prominent public presence, on valuable land donated by wealthy supporters, belonging to the private institution of the Sangha, upon which regular formal religious procedures were carried out, and, yes, supporting a range of buildings for residences, gatherings, and the like. In English, we don’t use the word “park” for this, we use the word “monastery”.
The idea that in the 45 years of the Buddha’s life, mendicants lived entirely or primarily in the open air is utterly unrealistic. They would have begun building huts as soon as it started raining. I’ve stayed in “parks”, and they’re great … until the rain falls. Then they’re miserable. Anyone who has lived as a monk would know this. There’s a reason why “dwelling in the open air” is a special and limited ascetic practice.
And for Wynne’s:
Buildings are hardly mentioned in the Suttas, but the Vinaya has more material on it - although this probably only indicates that the Vinaya is generally later than the Suttas.
Yes, the Vinaya is generally later than the Suttas, and represents a somewhat more settled and developed time. But it’s excessive to say this is the “only” reason for the difference.
The Vinaya explicitly deals with the material side of monastic life. In most cases in the Suttas, the kinds of building people lived in don’t really matter. When I’m teaching Dhamma, how often do I mention my dwelling place? I dunno, sometimes? But if I’m writing monastery regulations, I have to get a whole lot more detailed. That’s the point of the Vinaya.
So it’s not “only” lateness, it’s also the purpose of the text.
[*] I read an interview with him years ago where he said this. Maybe he’s been to India since, but he certainly hadn’t when he wrote his influential essays in the 80s.