Some people say Abhidhamma is a “later addition.” That is the approach taken by those incapable of comprehending the deep Abhidhamma. Only a Buddha can provide such a detailed and self-consistent analysis of how the mind works.
You seem to be mostly right. When I was researching this issue online, I did see some Dhamma teachers that seem terrified of Abhidhamma and they say it is better to not spend much time in it by claiming “Buddha didn’t teach it.” This monk is an example: Abhidhamma was not taught by the Buddha
Interestingly though, someone like Bhikkhu Bodhi who wrote a book on Abhidhamma also said he agrees with that assessment: The Theravada Abhidhamma with Bhikkhu Bodhi (Class #1, 5 Mar 2018)
- Bhikkhu Bodhi argues that there is no mentioning of Buddha teaching Abhidhamma to the monks in the Suttas. Rather, it occurs when monks are having discussions with each other. (Start watching from 6:24)
- In the page Abhidamma – Introduction, you provide clear evidence from different parts of the Tipitaka that all 3 Pitakas were recited at the first Buddhist council, Buddha did spend time in Tavatisma realm, and in one story, it is even directly mentioned that Buddha taught Abhidamma to the devas in Tavatimsa.
- Above combined with the fact that Abhidhamma seems fully consistent with the Suttas do suggest that Buddha did teach Abhidhamma.
- But you also state in the above referenced page: “The minute details on the structure of a citta vithi (a series of citta) of 17 thought moments, with each citta lasting sub-billionth of a second, can be seen only by a Buddha.” If you don’t mind me asking, how did you come to this conclusion? Is it mentioned anywhere in the Tipitaka that such intricate details can only be discovered by Buddha? Is it not possible for Arahants too?