I really don't get why would someone choose to spread his money over multiple coins to avoid risks when obviously it's not going to do anything.
And who do you think constantly keeps that story alive if not all those who invent some new super projects and are looking for new naive investors? The higher the price of Bitcoin, the easier it is for them to talk about diversification as an insurance mechanism, which makes no sense because of what you explained.
As for calling Bitcoin the king, I would not agree with such a title in any context because it does not reflect what Bitcoin represents, and also implies that there is some kind of kingdom that someone surely wants to conquer. The whole altcoins industry has never had nor will it ever make sense in the sense that it can change the relationship one has towards Bitcoin when it comes to trust and real decentralization.