When it comes to expressing the idea of "piling on", there are a number of different phrases that can be used to replace this term. Some possibilities might include "heaping on", "adding insult to injury", "overwhelming with criticism", "piling up the blame", or "dogpiling". Each of these phrases carries its own nuances and can be used to convey a slightly different meaning or tone depending on the context. Ultimately, the best synonym for "piling on" will depend on the specific situation and the writer or speaker's intended meaning.