Wrong. I can now see that altcoins deployed in a real world setting is beneficial for Bitcoin. In a Bitcoin testnet you cannot really now how new features will turn out in a controlled setting. If these features were deployed on an altcoin with real risk of losing real value in case something goes wrong then there is a lot more to learn. Think of it like beta testing for Bitcoin. The latest Beta test would be the deployment of Segwit then LN for Litecoin.