The problem there is that Apple's marketing speak of "unified memory" creates different and confusing connotations.It is not as surprising that modern chips stack or tile dies together, such as on phones and the like.
edit: Note also there is historical precedent for specialized SoCs that integrate DRAM on the same ASIC, see eDRAM: https://en.wikipedia.org/wiki/EDRAM
Your argument also require the reader knowing the technical premises that CPU and RAM processes are different nm, and that processes of different nm cannot be done on the same chip. These are not obvious or even absolute facts to anyone.
Actually a good place to find these sorts of citations are tech magazines that explain these new things, maybe like Ars Technica used to (i.e., a piece on "What is Apple's unified memory"), or else in academic research that sometimes studies contemporary chips, their research papers might have a blurb discussing the actual hardware architecture of such and such company's design. Or maybe there's an EETimes piece discussing Apple Silicon technology in one of their back issues, e.g. in trade journal literature.
So, what is well known varies depending on the audience. It is both plausible, and appropriate, for technological ambiguities and details to be explicitly discussed and clarified, either by the maker or by other journalists and writers.
And finally, consider also what is well-misknown. If you go online and look, lots of lay comments since Apple Silicon really do believe they are literally the same IC chip. So you have to ask how did that come to be?