Benedict didn't write the Hallowed Blight journals.
So there are two different persons in the lore:
a) Our friend Benedict Baker, presumably a journalist or detective, who embarked on a journey to investigate the Macmillan Estate missing cases in 1956. He did a thorough library research beforehand and was at least to some extent aware of what he'd get himself into. During the Lore stream Mathieu carefully put that Baker still is a valid survivor in the Entity's Realm (while Vigo no longer is). Also, it's my personal assumption that the Clown was the very first killer Baker ran into;
b) The researcher who discovered Vigo's lab and wrote the journal entries during Hallowed Blight. Seemingly they got involved in some affair in an opium den ere being pulled into the Fog. They had no idea what was going on and had to follow the only source of information they could get. Their obsession(?) with experiment and injection also comply with the image of a stereotypical drug addict. I imagine them as a 30's artist who sought relief or inspiration through medication and, maybe, would record their opium dreams for later reference? Only this time things had gone too far.
There's obvious distinction between Baker and the researcher's writing styles and even their personalities. People often refer to them as the same person, which confuses me. Did the devs confirm anything anywhere? If not, then the wiki page stating that Benedict was the one going nuts about flower serums is quite misleading.