In the past, wasn't it normal for journalists to have a particular specialization (even if that's not the _only_ thing they did), like "science reporter" or something? It is obviously impossible for every reporter to become an expert on every single topic that they might ever cover, but it is not unreasonable at all to get enough of a background on a topic that you cover regularly to be able to ask intelligent questions.
If news organizations were serious about this, they might actively look for people who _do_ have greater amounts of training/experience in a given field.
It may be true that in the current journalism paradigm the kind of skepticism called for is impossible, but it is absolutely not true that this is a fundamental state of journalism and that reporters could never become capable of doing it.