senior editors and baseline quality
In the FA process, they frown upon featuring articles that are entirely reviewed by a single WikiProject. The idea being that as you get a bunch of different opinions in there, you're more likely to weed out bias. That, combined with a commonly held idea of "NPOV", keeps our best articles in pretty good shape compared to most trash on the Internet.
Baseline quality is harder. If we want a lot of articles to meet the baseline, we need a process that's going to be a lot less bureaucratic than featured articles. But that means it's going to be a bit more vulnerable to the whims of individuals. This is a hard one to deal with. Maybe the standard for baseline quality will unfortunately be soft on POV: that a baseline article should be neutral in that it covers multiple viewpoints in a neutral tone, but not necessarily neutral overall.