Bungie had a major disconnect with a lot of the community and how the game was actually played.
They stubbornly insisted for years that the SMG was an appropriate and balanced starting weapon on all maps (it wasn't).
They claimed they were prepared for modding on disc maps and had it covered (they didn't).
They did eventually counter most of it with 1.5, but it kind of hurts when the entire console has been compromised in terms of security.
They insisted that modding and standbying were rare and not major issues (they were).
They never said this to my recollection, and explicitly set up an email
h2cheats@microsoft.com (still seared into my brain) for people to report instances.
The claimed the ranking system was unfair and that Halo 3's system was an improvement (it wasn't).
ELO is provably broken. The sport it was originally invented for no longer uses it. ELO was made to be quickly calculable on pen and paper by humans, but has many issues related to making it easily calculable like that. There's no reason to use a simple broken system when you have servers available that can crunch super complex math in seconds, considering many more parameters.
For example, in ELO, you can actually be punished for winning a game, rank-wise. You can literally enter a game and every option you have (leave, lose, win) will derank you. How is a ranking system like that fair?
And, as anyone who played against them online will testify, none of them were particularly good at their own game.
So you played against a small tiny fraction of players at Bungie, which proves nobody at Bungie was good at Halo?