Bhante in Buddhism probably like Christianity new traditions about certain doctrines are always attributed to the the founder.
As we see in the sutta of chanting together. It was Sariputta who made the sort of 1 till 10 detailed explanation of Buddha’s teaching. And at the end Buddha approved.
And like I said Buddha says in sutta that Sariputta gives more detailed discourse than himself. All the hint are in the suttas
Buddhism is like Christianity. Whatever was passed down as tradition stays tradition. But the reality have to be searched for.
For me. The info I got from suttas is indicating that Abhidharma was probably the way Sariputta taught. I mean the early basic ones. This I got from the suttas. That indicate that Sariputta had a wisdom focused group. And that is actually the tradition of Abhidharma.
Because his way of teaching is supposed to someone attain the first Path
That’s why some Abhidharma style commmentary has a way to make immediate illumination.
But the second book of Sarvastivada is the earliest of them and it actually already focus on that Chanting Together teaching style. So I understand from there started all Abhidharma texts. From something Sariputta organized infront Buddha.
We have in Theravada supposed earliest text but seeing Indian text is what shows what happened.
Saṃgīti-paryāya-śāstra, by Mahākauṣṭhila / Śāriputra
The ‘recitation together’, composed by Mahākauṣṭhila – according to the Sanskrit and Tibetan, or Śāriputra – according to the Chinese sources. The Chinese recension was translated by Xuanzang: T26, No. 1536, 阿毘達磨集異門足論, 尊者舍利子說, 三 藏法師玄奘奉 詔譯, in 20 fascicles.
Structurally, the Saṃgīti-paryāya is similar to the Dharma-skandha, though earlier, as the latter is mentioned in the former. It is basically a mātṛkā on the early teachings, arranged in groups of dharmas by number, similar to the Ekottarikāgama.
This text, as the name implies, is essentially a commentary on the Saṃgīti-sūtra (T 9, Digha-nikāya no. 33). This also indicates that the contents are more a gathering together and assemblage of the Buddha’s Dharma, than any new theory or discussion. The background to the first recital of the Saṃgīti-sūtra, as the Jainas fell into disarray after the death of the Mahāvīra, and the Buddhist Saṃgha gathered together to recite the core teachings of the Dharma to prevent such a split in their own religion, perhaps indicates the fear of present or impending schism arising in the Saṃgha on the part of those who compiled this Abhidharma work, some time later.
So my point is like happened to a prophet living in desert in getting illumination happened before to Buddhism.
To that you to know history
There was a time in India the tradition was persecuted probably that when real tradition is lost and the new generation have to create new belief.
And another way to see it easy is because all sources don’t agree.
And there is tradition also that Indians attribute a work to the person who inspired the writing of the text. But it doesn’t actually mean he wrote it or created it. It’s weird