The metaphorical ‘wardrobe’ is, in this instance, the Hosting Account. It is the main account through which all of the Virtual Servers are based. If you think of the V/S as a ‘coathanger’ (and the web site as the ‘coat’) then without a wardrobe there is nowhere to store the coat hangers – this is the same for the relationship between a Hosting Account and a Virtual Server.
Once a Hosting Account is set up then the client can order as many Virtual Servers as they want. If the Hosting Account is closed however then the Virtual Servers will also cease hosting.