I feel you and that’s where I worked actually for my short time there. In reality, the hotel and third party systems are both ancient. Sure they get rewritten, and things get upgraded, but it moves at a glacial pace because anytime an update happens everyone needs to sign off on it. Even the “API”, last I worked there, was still SOAP if I remember correctly, and while we did our best to make sure what you were booking was correct, we were beholden to the ancient infrastructure below. So it’s not malice, but it is rather hundreds of small tiny issues that propagate and bubble, each of which usually require everyone agreeing on the implementation change, and all result in the customer being pissed at the front desk.

Long story short, when you add a middleman there’s an entire layer of complexity added, and so I recommend skipping that added complexity and booking with the hotel.