If I recall correctly, he meant that multi-threading wasn't a direct goal, but a "side effect" of rewriting some parts of the codebase to match the expected con

If I recall correctly, he meant that multi-threading wasn't a direct goal, but a "side effect" of rewriting some parts of the codebase to match the expected conceptual flow, and paying off some re-write debt that had been accumulated after years of new features being "tacked on".