I have seen people do this as well. To me it all depends on how much variety you can offer your chameleon. If you have a slew of other feeder items, then I don't see it as a problem. But, some people don't have access to such variety, so it is important to feed what you can so your chameleon doesn't go on a hunger strike out of food boredom.
I like to mix mine up as much as possible. I will agree that crickets are not my favorite...especially when you realize how great dubia are as far as smell is concerned. I give my guys grasshoppers, katydids, mantis, superworms, silkworms, hornworms, hawkmoths, stick bugs, various kinds of flys....so to use just a gut loaded dubia or cricket as a staple wouldn't be out of the question. So, I don't think there would be any negative effects of doing just one or the other as long as you threw in some variety here in there for nutrients sake. Just IMO.