Here, I'll help.
This is the context object for my account:
https://gist.github.com/dclements/cbb5b19e148a913392af26213a8e5495
Now, you can tell me "but you can omit the context object under the spec" all you like, but _because things other than ActivityPub are being used, other specs also apply_.
I can also point to parts of the minutes for the discussion in building AP in the first place where entire features were punted to JSON-LD such that you need to use JSON-LD for, e.g., _language support_.