Bungie’s ‘golden age’ wasn’t quality, it was circumstance. They always dropped their games into ecosystems where they were mostly people’s first. Pathways on Mac, Halo on Xbox, Destiny at the advent of live service. They didn’t outclass competition, they benefited from lack of it. Halo wouldn’t even crack top 100 if it launched on PC alone.
That's why new halo games are shit. Not because quality declined with time, but because it's no longer launching on a new platform with zero competition, and it just can't hold up when it actually has to compete against the rest of the industry on an established paltform.