IIn New England, masonry steps just don’t seem to survive the freeze thaw cycles or the salt that people apply to them. When water migrates between cracks and mortar lines and it freezes it expands and cleaves apart the masonry. Frost heave is when water in soil freezes and it expands and pushes the soil upwards. To prevent frost heave a masonry stair case needs a full foundation, one that has a footing that is four feet below grade to be below the frost line. This makes them very expensive. Most likely that is why most people here in Massachusetts use wooden stair cases outside their residential buildings.
Wood stair cases eventually rot but are much less expensive. Wood stair cases may be attached to a building or a deck at the top but at the bottom they rest on grade. Wooden stairs can frost heave in the same manner as masonry if they do not have a foundation or footing. Most use concrete filled Sono tubes. I have replaced many exterior wooden stair cases that have rotten away. The errors are always the same.
The problem is always with the stringers and the footings. Stair stringers have an inherent problem because the tread cut, and riser cut result in exposing end grain which is susceptible to rot. This can be addressed by applying 2-part epoxy or lacquer-based paint. I have come across some stringers in which the builder placed felt tar paper over the end grain on the stringers and I have noticed that they had less rot.