It Works... But Why?
Every developer has done it — copied a Stack Overflow snippet or an AI-generated block, dropped it in, watched it work, and moved on. The code runs. The bug is fixed. But if you can't explain why it works, you've borrowed a solution, not learned one.
There's nothing inherently wrong with using existing code — no one writes everything from scratch, and reusing solved problems is a core part of being productive. The issue isn't the copying itself; it's the silent gap it leaves behind. You solved today's problem, but you didn't gain the understanding that would let you solve tomorrow's variant of it without going back to search again.
Debt That Compounds Silently
Unlike technical debt from messy architecture, this kind of debt is invisible — it doesn't show up in code reviews or slow builds. It shows up months later, when a similar bug appears in a different context and you're stuck, because the understanding was never actually yours.
