I mean - they’ve had teams working on Fallout, ESO, and Starfield simultaneously. What work was probably going to be dedicated to ES6 probably got transitioned to ESO or Starfield. They’ve definitely had multiple teams focused on multiple things - ES6 just got deprioritized.
Prior to ESO, though, Elder Scrolls was a franchise entirely marketed at people who wanted single player RPG experiences.
Even if it’s still Elder Scrolls content- a good portion of that original market is not going to have interest in a multiplayer experience. Or a subscription experience. Or a”live narrative” experience with gated content windows.
It’s a very different experience at its core, so while there may be an overlap between the two markets in the Venn Diagram, it’s still a very different market segment than a pure single player outing.