That logic is true of "contributions" - here's some undocumented code, it seems to fix my own poorly specified problem, I have no idea how it works, please merge.

For bug reports (at least IMO) a minimal example to reliably reproduce the error without any fuss is the basic building block. The reporter doesn't need to understand why it works let alone offer an explanation. In fact for complex projects more often than not any purported explanation will be subtly incorrect and actively misleading. If anything further "documentation" of bugs is unwelcome. Unambiguously demonstrate the defect and GTFO.