Critcizing "dogpiles" as inherently "moblike," destructive, negative, and childish without considering the content which has evoked this response has the same in-built political and structural issues as the demand that oppressed, discriminated, or harassed groups moderate their tone before their objections will be considered. Both actions attempt to codify behavior while treating speech content as empty; they ignore power differentials; they treat actions or speech acts as if they take place in a vacuums free of social circumstances, historical knowledge, or political influences, rather than as if they are what constitutes or destroys communities.
There is no polite way to tell someone you do not care about the genocide or oppression of their people. There is no polite way to make rape jokes. There is no polite way to use "gay" or "girl" as a synonym for "bad," "weak," or "ugly." There is no polite way to blame a victim for their own harassment or abuse.