It can generate revenue, but not good revenue. What Rated D is saying is that for the size of the fleet and market ASK's - the revenue generated is poor i.e. poor unit revenue or rASK. JQ also yields poorly - which matters. It might make sense to redeploy capital to, for example, Qantas - where a better unit revenue/yield could be achieved, even on a higher cASK.
And this is the inherent problem for most LCC's - hence their diversification and investment in other revenue-generating areas. Air Asia is a good example of poor financials and a focus on creating the worlds largest OTA, and even selling other airlines via their site. Exceptional airlines like Spirit in the US - earn 45% of their total revenue from ancillary sales - not tickets. And this is the trend. I think JQ is around ~25% of revenue is ancillary sales...