I cannot imagine being so hostile towards curiosity. You approach this as "I already know everything there is to know, and therefore this documentary (that I haven't seen) has no value".
I was merely citing the known facts in this case. The facts have been well-established in the criminal trial and in the press coverage about Holmes. The facts are voluminous, and of all this mountain of evidence, very little of it is featured in this so-called documentary.
that's not what this documentary is about
I am under the impression that most people are not watching this movie to find new evidence or dispute the trial outcomes. Like other commenters have mentioned, many people seem to be watching more out of a sense of curiosity, similar to wanting to see a magician reveal their tricks.
One additional reason people watch documentaries is to get tl;dr in fun form. Not everyone was obsessed with Holmes enough to read all of that.