I've used ones that do a great job.
They don't want to be liable if the setting for popcorn burns their popcorn. Some people would blame the brand of popcorn.
I still use it and it works great.
Who in the world would want to eat that dirty popcorn? I only use clean kernels to make air popped corn in the microw all you need is a large glass bowl with a cover. cleaner cheaper very healthy.