Whether hard water destroys appliances or not, very much depends on how hard the water is. Extremely hard water will quickly coat wetted surfaces including valves, heating elements, and pipes, and this can have obvious negative impacts on system performance. The surfaces that get coated the fastest are ones where you have an air/water interface or surfaces that are wet / dry / wet / dry.
Water hardness is most typically measured as Grains per Gallon (GPG). In my experience water that has less than 7 GPG is fine. If the water is harder than about 12 or 13, it will eventually have some impact on appliance performance. If it's harder than 20, this will have an impact pretty fast and we've seen appliances (usually dishwashers) fail in a couple of years.
You can look up your actual water hardness for your city or town here to get an idea of how hard your water is and how much of a risk it might be to your appliances:
https://www.aquatell.ca/pages/aquatell-canada-and-usa-water-hardness-charts
