It's ultimately the studio management and Microsoft who set the release dates. It's job of the project lead to communicate to management what the state of the game is and if it will be ready. If this communication breaks down you can have a situation where the developers don't think the product is ready for release and management think everything is fine.That game was coming out simultaneous with the Xbox launch. What they showed, minus the last minute tweaking for frame rate that most games get, was what we were going to get. It was set for fall 2020 at the very least, maybe November 2020 more specifically.
No one knows what anyone thinks, we're not mind readers, but given the fact that they were going to release it in that state, they were satisfied enough to push it out the door. If that isn't being done, I don't know what it is.
So they knew the game had issues bad enough to delay it for an entire year or lacked this self-awareness to know what they made was bad. It doesn't matter which it was; both speak to the quality of that studio.
According to Jez Corden that's exactly what happened to Infinite. According to his sources, the Creative Director Chris Lee was hiding the true state of the game from Bonnie Ross and the Microsoft higher ups. So when the E3 showing came, the shit hit the fan when they released the game was nowhere near ready. The result was that Chris got fired and Staten was brought in to replace him. So you can't just assume that 343 as a whole were happy with the state of the game from the decisions taken at the highest level in the studio.
That might seem ridiculous, but think about a title like Cyberpunk that got to launch, was given a pointless 3 week delay, and then arrived in a functionally broken state. Like did the developers of The Witcher 3 think there was nothing wrong with a game continuously crashing and playing at 20 FPS or lower, and that's just their regular quality bar?