Can you share where 343 promised to have online matchmaking for campaign co-op?
No, but they promised a lot of other stuff they didn't deliver.
This is just another point where they underdelivered, even when not explicitly mentioned.
The details don't matter anymore.
343 has a history of overpromising and underdelivering and until today they have done exactly 0 against that.
Fans gave them a second and a third chance. The benefit of doubt again and again. Yet they keep doing the same.
Apologies are meaningless. "we hear you" is meaningless, if actions don't follow at some point.
And over a decade later, there is still nothing in their favor.
An AAA developer, making SP/MP games with reviews that hover in the 80 - 90% range. Last game at 87% MC with 17 GOTY awards.
Have a look at Rockstar, Naughty Dog, Sony Santa Monica, Playground Games, Foam Soft, CDPR, Nintendo EAD, Respawn
Those are top tier developers. 343 is not in that league.
And i doubt they ever will. They need at least another decade to change their reputation and vita anyways.
Or just compare how The Coalition took Gears over and delivered compared to 343 that took Halo over.