I think this is a different matter. "Sections" in MIB are actually addresses of SNMP variables. The structure is intended for computer parsing. Most (all?) MIB browsers represent it as a clickable expandable hierarchy rather than a running text. This is like a hierarchic file system: my computer probably has even deeper nesting of directories and files.

Standards, on the other hand, are intended to be read and referenced by humans. However, a human cannot easily spot the difference between 9.6.1.3.4.9.3.2.1.1 and 9.6.1.3.4.9.2.1.1, which defies the purpose of section numbering.