I sat for 15 years a law machinery, the cleaning tablets have never led to any disturbances. A "clean" without the tablet also does not solve the fats contained in the coffee and oils that adhere in the machine and become rancid with time. In this respect, clean without detergent like oily dish wash without Pril. So pretty stupid. And on top of that unhygienic. Lecker Schimmel and Ranzefett.
I can from my own experience (with an excellent coffee, not the cheapest beans from discounters where you can not taste the difference) that the coffee tastes better after cleaning - when cleaning with tablet.
I hope this puts the prefaces something. They were not really thought through in the final analysis.