I know what it was, but why do people care? And does it have anything to do with Daggerfall?

Id assume because countless lives were lost during it and it [censored] with the very fabric of time.

Wait, who said this? And it has everything to do with Daggerfall. I'm not very good at explaining things so I'll leave that up to the IL:http://www.imperial-library.info/content/oblivion-warp-west

I meant what does it have to do with lore? Did it retcon Daggerfall or something?

No, the Warp of the West was a result of the events of Daggerfall.

The Warp in the West was to have continuity between Daggerfall and Morrowind without making one ending of Daggerfall canonical and disregarding the rest. It made all endings of Daggerfall canonical. They all happened at the same time. It's not something Bethesda should strive to do intentionally, as it's a very complicated thing and it's just asking for major plotholes.

ahh my bad, I misunderstood what you meant. Indeed, Velorien said it all.

Thank you very much. I thought it was something like this, but I wasn't sure.