An actionable list, not a graveyard for ideas.
Backlogs are often graveyards of good intentions, with promising ideas buried under vague stakeholder suggestions, random customer feature requests and engineering wish-list items.
The fix is to keep separate areas for items at different levels of maturity, and to enforce different policies for each. Idea Banks sit before the real backlog — a holding place where raw signal can mature, accumulate evidence, and prove its worth before competing for engineering capacity.