Why exactly does a perfectly competitive market depend on consumers having perfect information about a product?
Perfect information implies every buyer and every seller knows everything in the market. As soon as a firm brings a new product to the market, other firms start selling the same, identical, product. In practice, say a kebab shop comes up with a secret new ingredient and attracts more custoemrs, but as soon as this happens, other shops copy it. Bottomline: any information-advantage is short-lived in perfect competition. This also leads to the other characterisation, all products are homogeneous. 

If the firms/customers do not possess full information about the market/products, then you should characterise the market differently i.e. oligopoly, monopolistic competition or monopoly.