Is there such a thing as a "pure" documentary film?

Is there such a thing as a "pure" documentary film? Many of us assume documentary films portray real people taking part in real life events shown from an unbiased point of view. Unfortunately, there are many ways a documentary film's integrity may be compromised. It is important to remember that in most cases the individual making the documentary film has his/her own agenda and perspective that they wish to convey. It is rare when a documentary film is not biased to fit the filmmaker's own point of view. The filmmaker may manipulate the audience in their use of film angles and editing cuts, the film's musical score, or may delete portions of interviews to conceal any statements made that don't agree with their own perspective. Often times, the film's sponsors may have certain requirements on how the finished film turns out, in order to fit their own agenda. In some cases, the subjects themselves have input into how they are portrayed in the final film product. Also, keep in mind the simple presence of a camera crew will often times cause the subject to behave in a manor inconsistent with how they would behave otherwise. In my opinion the least realistic documentaries are the ones that seem to focus on the filmmaker themselves. It's hard to create an unbiased film when the prominent subject of the film is yourself. To me, the performative and participatory modes seem the least true to life. A recent trend in documentary films seems to be attempting to make a star out of the filmmaker as seen in films such as Roger and Me(1989) and Super-Size Me (2004). It seems to me that in order for a documentary to be truly "pure" it would need to be compiled solely from surveillance camera footage with the subjects being unaware that they are being filmed. Furthermore the film's sponsors as well as the filmmakers would have to be wholly neutral on the topic that their film addresses, with the film giving both sides of the issue equal consideration. While these conditions continue to not be met by documentary films, I will continue to view them as glorified propaganda films.