Joules probably do well on Q for that reason, as in their direct supply chain you guarantee people wait for the item of desire to rotate through whatever their weekly sale is (£94 for a Fairisle Jumper isnt going to get the tills ringing until it drops in price). Obviously as a company they've suffered losses this year, so it's for those kind of companies as you say Q holds value - but then again many stores and brands have also cottoned onto the concept of an "ebay outlet" now also for similar reasons.
Am guessing the reason we don't see the likes of Joe Browns on Q anymore is that whilst they are a brand that seem to sell everywhere, in recent months they've gone out of their way to ensure they are excluded from any sales / discounts the retailers they are sold through, thus not making them attractive to Q anymore.