1) The journalist's work is sometime a soul-crushing effort to turn complex things that can't really be made simple into a readable summary. I cover Quantum tech as someone who has at least a grasp of physics: it's insanely difficult.
2) Journalists that behave like the ones you describe, are bad for the whole profession. What you describe is a systemic problem in journalism, which I think it's especially bad in the big newsrooms of big newspapers that are struggling to survive or have still to figure out a proper business model for their future.
That said, I think there are a lot journalist who, like yours truly, tend to stick to what they've studied and know. I would never write about medicine, but I know I'm able to write about tech avoiding the complete lack of knowledge some colleagues show. The real problem: this works for me as a freelancer. Staff writers are considered fungible, and they have to adapt to whatever needs to be written.
Sorry for the sparse thoughts, I have to much in my mind about this, but not enough time to put it down properly right now. I still wanted to chime in, though. :)
P.s. Journalism schools are also part of the problem. They form a cohort of people who think they can do exactly that: write about anything. It's bullshit, and it does not work well for the category. The best colleagues I know all come from very different study fields, and they sort of fell into journalism by chance.