> I’ve always been a big believer in rebuilding your product from the ground up. I think it’s something you should always have going on in the background. Just a couple of devs whose job it is to try and rebuild your thing from scratch.

Their time is much better spend working on improving the "legacy" codebase. Simple refactoring and splitting the codebase in a modular fashion, mean you can work on limited parts of the system in isolation. This makes incremental improvements and switch to new tech much easier, and certainly less risky than a rewrite.