Note: This is meant as a question about the historical development of LaTeX conventions, and how they influence Editor design, not as question about how to implement it differently.
One of my pet-peeves about LaTeX, is how editors treat
\paragraph as the next level below
\subsubsection. While this corresponds just fine to how it is implemented by default with
\toclevel@paragraph=4, it strikes me as an odd convention.
To me, the concepts of paragraph and (sub)nsections are entirely distinct, with sectioning defining a top-level structure of the document, and paragraphs/subparagraphs describing a separate layer of structuring within a given (sub)nsection; It doesn't make sense for a
\section to contain a
\subsubsection directly, but it does make sense for it to contain
\paragraphs. This view is mirrored by the standard setting of
\paragraphs not appearing in the table of contents, not being numbered, having their title styled entirely different from sections, and simply by having a distinct command-name pattern.
Now, as long as no deeper nesting than subsubsections are needed – and it is probably bad style to have a deeper level of nesting in final documents – this distinction doesn't matter much. It does however start to matter, when editing document structure with editor tools ("promote/demote subtree"), as they tend to convert subsubsections to paragraphs and vice versa. (Depending on the editor this can be changed though.)
So I was wondering, how did that convention come about?