They don't get their income from camera companies at the moment, they get them from YouTube advertising, so they make their money pushing out as many general appeal vids as they can in a month.
Jason Lanier is salutary - he took Sony's coin, became perceived as biased, his viewers dropped off, and he's lost his sponsorship. Not sure where that leaves him. How do you come back from that?
DPR I think are incredibly problematic.
As Amazon's propaganda arm, they both do reviews of camera gear and sell the stuff. That's conflict of interest, right there.
It'd do my head in if someone could also show they accept advertising money from camera manufacturers.
Everyone tries to monetize. This site has affiliate status of some kind with B&H and Adorama, for instance.