> I've never understood why certain philosophers view computation as some kind of abstract symbolic manipulation

Possibly very early AI misled people here. In the 80's, a huge amount of AI was logic manipulation; "If A then B is valid"; "A is true"; therefore, "B is true". It's not hard to see how people would conclude that that sort of symbolic manipulation could never result in consciousness.

But modern neural nets aren't like that at all. Calling modern neural nets "symbolic manipulation" seems insane; like calling libraries forests, and insisting we can apply scientific principles about forests to them, because books are made of trees.