My personal experience is not so much that they really help cleaning, but it seriously has reduced certain types of problems with my machine. If you have fairly soft water in your area, rare in the U.S. btw, it may not help at all. I have much less need to descale the machine and certain parts that are prone to problems from scale are almost problem free and I mean FOR YEARS. I very rarely descale my machine and when I do I just use vinegar. Honestly, I don't really even keep up with my softener as much as I should, but it is clear it makes a big difference in things like thermal relief valves, the high pressure solenoid, the high pressure orifice, less jet clogging, and less clogging of jet strainers with scale build up. It also of course keeps the heat exchanges more free of scale so that they generally perform better on a heat exchange machine. I do believe it may help to leave certain fine fabrics in rugs, carpets, and upholstery softer to the touch, but that's about it. I would never take mine off!!! I well remember the problems I had before I installed it.
Ive run softeners for years. You could take any fitting apart and there would be no buildup of anything, so yes I would say it is worth it. Granted we do have soft water in our area BUT if my Water Pond does run out of water during the day and I needed to hook up to a customers faucet there are nearby communities that have very hard water let alone be out in the sticks where they have well water (especially outside water faucets)
I have never descaled except for the one time that Jon Don did it for me at an annual maintenance. Although I told the manager that no descaling was needed evidently it didnt get passed on to the tech.
Charging the softener it is part of my monthly maintenance so I havent thought twice about it.