You're right, Mr. Balls. I am somewhat of a purist. I don't think the jarred roux are awful by any means and I wrote a recipe that I call "Cheater's Gumbo" specifically for someone who wanted to make it, but was not much of a cook nor who had any desire to try to make a roux. She also had two young babies and lack of time. The jars are much better than the bagged stuff or the dry rouxs to me. Jarred roux is not unacceptable. I don't know what's in them that I taste and can only surmise that the difference in the oils used by the manufacturers and the oil used by me is what I'm tasting.
Most people probably wouldn't know the difference, but they probably use tomatoes in their gumbo, too.