Suppose I have several three sections in my document, S1, S2 and S3, which styles St1, St2 and St1. Now, I may want to: * Change the styling of S1, without the edits affecting S3. * Edit the style St1, so that my changes affect both S1 and S3. In LibreOffice, I can only do just one of these, via Format > Sections... > Options... . And even that is rather vague and low-discoverability, plus, it won't tell you whether you're editing the named style, or whether your changes will only affect a single section, possibly by creating a separate style for it (which should possibly be another bug). Anyway, section styles should be bona fide styles just like paragraph styles, character styles etc. - where you can DF, you can apply a named style, and you can edit a named style.
While there might be a few scenarios where consistently switching attributes of a section on or off are desirable it is an over-engineering and with negative effect on usability since many features such as columns are also available with other, full-fledged entities, ie. the page style. And ultimately I doubt that a section style is introduced for the document standard.