Hey plan.md mostly will be a static file that you manually have to maintain. It won't be relational and not be able to form connections between info. You can't recall or query intelligently? (When did my preference change?)

CORE lets you - Automatically extracts and stores facts from conversations - Builds intelligent connections between related information - Answers complex queries ("What did I say about something and when?") - Detects contradictions and explains changes with full context

For simple fact recall, plan.md should work but for complex systems a relational memory should be able to help better.