I get that. I just always used homebrew (which I believe the majority of tables still do), so this was never a problem for me. The settings were chapters in a cool story and ideas for home games. None of us felt the story in the products hurt our gaming experience.
Here's a story where metaplot caused actual problems for me.
I was planning on running a campaign in the Forgotten Realms, and I had been reading through the 2e boxed set to figure out what region looked best. After some thought, I settled on Tethyr, because I figured I could get quite a bit of juice out of the civil war going on there with numerous nobles all jockeying for advantage, while the PCs could help the downtrodden and/or ally with one warlord over the rest and so on. That seemed like a cool campaign premise. And hey, there's a new boxed set out that's about Tethyr and Amn,
Lands of Intrigue. I'm sure that's going to have lots of useful info on the different warlords and their territories, let's check it out.
And then I learn that no, the civil war is over. One of the nobles went off to Waterdeep to recruit mercenaries and allies, and while she was at it she married the Rightful Heir to the throne who had been hidden away and had spent the last decade or so in hiding as the
scribe to frickin' Elminster! So now all was well in the new realm, and all the former warlords had either sworn fealty to the new King and Queen, or been either killed or sent into exile, and the low-level ranks of nobility had seemingly been removed and replaced with elected Sheriffs, and I don't know what else. And all that happened off-screen in some novel trilogy.
Needless to say, that campaign didn't happen.
Eberron is a horrible comparison because it's been explicit from day one that the novels weren't canon, it's one of the reasons the novel line failed.
The opposite has been true of FR and Dragonlance, the novels have always been canon, it's a core part of those settings and part of why those novel lines succeeded, they actually meant something.
Given that TSR's novel line was the immediate cause of the company's failure, I'm not sure I'd say the novel lines "succeeded" when taken as a whole.
Yes, there were multiple causes, as there often is. But the actual blow that, in game terms, put TSR at 0 hp was that Random House got tired of taking payment for unsold novels in new novels that didn't sell either, and demanded that TSR repay them with actual money – money they didn't have.
You are allowed to like metaplots in stories. There are some serious ones out there including the Arrowverse, the Star Wars EU and Star Wars Disney continuity, the MCU, the Marvel and DC continuities, numerous video game series from Super Smash Bros and Kingdom Hearts onwards (and no that first one wasn't a joke).
I'm pretty sure that's not metaplot. That's just ongoing plot. Metaplot is, at least according to
Wikipedia, a term that's specifically about overarching events in RPGs.