When I was growing up, these seemed to be ubiquitous and I never liked them. They seemed overcomplicated for the purpose, and created a gross and smelly area under the sink that needed more cleaning.
I haven’t had one in years, as a simple sink mesh does the same job. But I don’t really know how other people are. Are under sink garbage disposals still common, and commonly actually used by people here?
It’s definitely not necessary. It can be convenient.
It wouldn’t be very high on my list of wants, but I’ll use one if available.
My problem was not using the thing for long periods of time and it kinda jamming in place. They have a little quarter-inch hex key hole on the underside that you can use with a hex key to get 'em going again if that comes up.