These are exactly the reasons I suspected why duct tape may not be the best choice but having never used it as a rimstrip, could never confirm. You have just confirmed it.

As KLX678 presented in a very humorous way, duct tape is an amazing product which has millions of uses. It is often a lifesaver when one has to substitute it for when a "normal repair" is not possible or feasible. Thus it may not always be the best choice especially when a specific product for that purpose is available. It's probably safe to say that the Armor Rim Strip is superior to duct tape or the stock rubber strip. Whether one thinks the cost is worth it is the question. I will most likely order a set the next time I change my tires.