Much like the -- in my view wrong -- idea that scientific writing goes without the first person, I regularly come across the idea that the passive form should be avoided at all cost. Never write "interviews were conducted", but always "we conducted interviews".

The interesting thing is that I do in fact agree to this example. Here, eliminating the passive does solve a problem that I agree is a problem that should be solved, namely the pitfall of rendering opaque who does something. Or more generally: the passive form potentially obscures some elements of a statement, simply because they aren't needed from a purely grammatical point of view. The phrase "interviews were conducted" is grammatically correct and complete, but silent about who did the interviews. In principle, this could be solved by adding the acting agent, i.e. us: "Interviews were conducted by us." This makes the statement both grammatically correct and semantically complete. Whether it is an example of eloquent style can be debated (I think it is not), but for a research report it does at least contain all the information it needs.

However, this points to a further nuance in the idea that all passives are wrong. I think they are not. The preceding example is ugly, but not wrong. Yet, it does perform a particular operation vis-à-vis the active version of "we conducted interviews": it puts the interviews upfront, and hence makes them more important to the reader, in relation to who in fact does the interviews. In this example of interviews, there is not much point in this alternative prioritization. But think about the statement: "The boy suffered from mental trauma because he had been neglected by his parents." The boy is most important here, followed by the neglect, and only in last instance the parents seem to matter. In my view, there is nothing wrong with writing this sentence with the passive form of "had been neglected". In fact it guides the reader towards what is most important in your message: the boy being neglected.

So, if you notice the urge to eliminate a passive, wonder what problem of vagueness that would solve, as well as which potential of clarity and guiding the reader it would kill.