low hanging fruit. There are papers that need to be written or have never been written simply because people see it as low hanging fruit and too easy or low effort. This issue for the field would be that people still want to reference something that says this simple idea in their paper. This means that the people who write these 'low hanging fruit' papers get cited a ridiculous amount for their simple, basic, bullshit paper.
collaborations. My PI (again, different field) is up there as one of the top contributing authors of the field and is easily what you would consider a prolific publisher. The has anywhere between 2-4 publications per year in high impact journals. And this isn't counting posters, presentations, or the occasional bonus authorship you get for just being around when that paper was written. She does this through constant networking with people and collaboration in projects. She is also more than happy to look at other people's long running projects and take out a slice of data and do a writeup on it. There are several projects people do that look at huge data collections, but then only analyze what they cared about and ignored the rest. Those become easy papers to write.