This is a weird example. If you have clear winning strategy, you can rely on it. But if you're training NNs, on many tasks you may not want them to fall into "r

This is a weird example. If you have clear winning strategy, you can rely on it. But if you're training NNs, on many tasks you may not want them to fall into "repeat what everyone is already doing". AlphaGo scored higher by playing some moves which people wouldn't. It's people who ended up adapting after that event. Depending on what you want to achieve, starting from random weights may be the better approach. And even in other situations, starting from scratch that be informative for research.