I am a full time digital nomad and stay in a ton of hotels. I have once gotten the same rate directly, usually it is 20-30% higher. Hotels basically force you to third parties.
Do they think that direct callers are more invested in their specific hotels while price comparison site users will just pick someone else if the price is too high?
Or the people handling bookings at the hotel have no discounting authority and don't care where you're booking from as it's not their problem anyway. "If you say it's cheaper on the Internet go book there!"