> "When you throw away code and start from scratch, you are throwing away all that knowledge. All those collected bug fixes. Years of programming work."

But, sometimes, that's exactly what you should do. It brings to mind OpenSSL after Heartbleed. I remember reading that the LibreSSL people were ripping out all kinds of stuff (like kludges and workarounds to support OpenVMS), and rightly so. You might call it "knowledge [and] collected bug fixes," but sometimes the crap is just crap.