I don't believe the statement because altcoins have their own market strategy on their marketing.
When Bitcoin drops, almost every altcoins are dropping as well but that doesn't mean that altcoins will become useless, it is just altcoins price value are being paired with Bitcoin, Ethereum or NEO but time will come that it will soon paired with other top altcoins so when that time comes, Bitcoin will no longer affect Altcoin price values.