I consider “x considered harmful” harmful compared to something like “I observe y and conclude x is harmful in expectation.”
The passive voice often obscures what actually happened or what the speaker/writer is describing. It also creates a sense of authority decoupled from the authority of the author. When you use the first person pronoun, the weight of the statement rests on your own reputation, rather than on some unstated group’s implied consensus.
That being said, sometimes the passive voice is useful, but I advocate that it only be used when it is not withholding relevant information about what is being described.