I love the scratch cake v. box cake analogy. Spot on.

Need to clarify an important point though. It's a frustrating (to me) source of confusion.

"Silver gelatin emulsions" is a big universe, covering not just space (i.e. products available commercially today), but also time (i.e. products available at different times since 1880.) That part is pretty general knowledge. What can be confusing are the very real differences between paper emulsions (almost all neutral, unwashed, unsensitized -- don't worry about what those terms mean now: all will be revealed! -- just think old-timey) and negative materials emulsions -- which range from basic dry plate to the most sophisticated modern film.

A basic paper emulsion (minimal tools and materials), well-coated, is virtually indistinguishable from commercial. I often compare a handmade recipe to Lodima paper and if I coat on glossy, commercial baryta, I have to make sure I take careful notes as I process or I won't able to tell which is which after the prints are dry.

It's possible to leave "hand of the maker" tells on handmade paper, but that is a creative decision, not a technical default.