I believe that would be the Voyages of the Princess Arc stories from Mystara. Although, to be fair, most of that wasn't really meta-plot but simply setting exposition dressed as fiction. Fun reads. But, AIR, there wasn't much connecting one story to another - they went to this place, saw these things, did those things and then moved on to the next place.
And, to be fair, both Greyhawk and Forgotten Realms saw a HUGE amount of setting development in Dragon magazine. But, again, no meta-plot. It was mostly just setting exposition - this town/region has this or that in it with these or those bad guys doing bad things. It was largely a 2e development that you get all the big meta-plot stuff. Dead Gods, Faction Wars, Greyhawk Wars, etc. And, again, to be totally fair, most of the 2e material wasn't meta-plot based. There was tons of stuff that didn't move the campaign setting forward but simply fleshed out existing parts. One of my favorites was the Faiths and Avatars books for Forgotten Realms. Those were fun reads.
But, all that aside, we have to remember that WotC isn't publishing libraries anymore. You get 5 (ish) books a year, 3 of them will likely be modules. There just isn't space to get into meta-plots, nor is there space to present an entirely new setting.
That's what DM's Guild is for.