Two recent docs I’ve watch have used this style. The Robin Williams documentary on HBO and the Netflix doc about Orson Welles last picture. There is very little narration, almost all the content is actual footage or audio recordings (much of it clear outtakes and other material that was not intended for release), cut together with interviews about the subject.
IMO its actually fairly irritating. It inevitably involves cutting together little unrelated snippets of audio and video that seem to be related to whatever the interviewee is currently saying. It makes it really hard to follow the events being described, and is IMO no more authentic to the subject matter than a traditional doc (the director has cut the audio and video together to tell the the story they want told, just as much as if it was a traditional documentary)
Does this style have a name? Is there a particular film or director that started what is apparently a bit of a trend in the documentary film community at the moment? Maybe it was done well originally and these are less well realized copies of the original?