Passive voice in itself is benign. It provides flexibility, and it lets you emphasize the target of an action, or the action itself over the do-er, if that fits your intent.
Advice to avoid passive voice comes from a variety of reasons, but perhaps the most charitable (and I think useful) view would be:
* In technical writing, you might have pick up passive voice because of misguided advice to use avoid "I" and "we". This naturally leads you to using passive voice all over the place. This makes the writing "seem more objective", but is really just the veneer of objectivity. And in some ways is the polar opposite of the advice to always avoid passive voice. English has both voices - use them both. If nothing else (and all other things were equal), active voice tends to be more concise - as you have noted - which is a true benefit for technical writing.
* Passive voice is one of tools employed when weaseling or obfuscating (see the infamous "mistakes were made"). Advice to avoid the passive voice is either nudging you to either... just be more honest (don't weasel!), or to be more clever in your weaseling (because everyone knows the trick...)
* Because use of passive voice in more mundane/banal communication is so common (or seemingly so common), there was a perception that people were just defaulting in the passive because that's what government officials, or companies or whatever talked like. And so the advice was pushback. Reminding you that you don't have to speak or write like a prepared government speech or press release.
Advice to avoid passive voice comes from a variety of reasons, but perhaps the most charitable (and I think useful) view would be:
* In technical writing, you might have pick up passive voice because of misguided advice to use avoid "I" and "we". This naturally leads you to using passive voice all over the place. This makes the writing "seem more objective", but is really just the veneer of objectivity. And in some ways is the polar opposite of the advice to always avoid passive voice. English has both voices - use them both. If nothing else (and all other things were equal), active voice tends to be more concise - as you have noted - which is a true benefit for technical writing.
* Passive voice is one of tools employed when weaseling or obfuscating (see the infamous "mistakes were made"). Advice to avoid the passive voice is either nudging you to either... just be more honest (don't weasel!), or to be more clever in your weaseling (because everyone knows the trick...)
* Because use of passive voice in more mundane/banal communication is so common (or seemingly so common), there was a perception that people were just defaulting in the passive because that's what government officials, or companies or whatever talked like. And so the advice was pushback. Reminding you that you don't have to speak or write like a prepared government speech or press release.