Close, but the logos were really styled that way, with ASCII brackets and slashes, on the cases.

https://en.wikipedia.org/wiki/Apple_II

https://en.wikipedia.org/wiki/Apple_IIe

But it's only for logo right? I don't think they should be used in text form, doubt even Apple themselves would do that.

No, they used it elsewhere. When the machines booted, they displayed "Apple ][, "Apple //c", etc. at the top.

I have an Apple II plus original reference manual here, and it uses “Apple ][“ (brackets) only on the cover. In the book text, it uses “Apple II” (Roman numeral) throughout.

Is that the red book with the handwritten notes, or the typeset one?

typeset - published 1979 by Apple

I believe these forms were used on startup (i.e. they were in the roms in text form this way).

As I recall, all print publications of the era used ][ and //

I remember typing it this way myself on the early BBS scene. Personally my system was a Radio Shack TSR-80 Model III. (That is III not 3)

People can be weird about this sort of thing, especially with Apple. I remember when the iPhone XR came out some people would insist on always writing "iPhone Xʀ", for example.