Bitcoin doesn't need altcoins because it was making its way by its own.Altcoins are dependent on Bitcoin which has been seen over and over again on every rise in price of Bitcoin.Bitcoin will always rule the digital/crytpocurrencies no matter how advanced they will be in tech but still will remain under Bitcoin
I somehow dont agree with you, it is true bitcoin still rule the crypto currency world, but that doesnt mean it can stay like this forever who knows one day it will be replace by other alt coins, despite that a lot of alt coin seems useless but i think its one of the element that keep cryto currencies world interesting, alt coin has help bitcoin a lot because a lot of people doing trading bitcoin with alt coin
i think he is mostly talking about the current existing altcoins, and i agree with this part only that the altcoins that exist today are highly unlikely to be any challenge for bitcoin. some of them come close in some aspects like XMR but in the end they can't take the market.