Is there any lore justification for being able to do previous expansion's sidequests?

[Brightamethyst]

I'm on EW, and I'm wondering if the WOL could conceivably time travel at will. I'm asking because I'm doing side quests from previous expansions and trying to justify the headcanon for immersion purposes. Basically, I'm looking for a way to explain why characters still talk to me as if I'm in ARR, HW, SB, or ShB, as the case may be.

It's not time travel. It's reading a book out of order.

Imagine you have a book. You read chapters 1 and 2, skip ahead to chapter 7, and then go back to chapter 5. That doesn't mean that chapter 5 happens last chronologically, or that chapters 3, 4, and 6 don't exist. Events happen in sequence regardless of what quests you do or don't do. The WoL isn't time traveling if you go back and do a HW quest at level 100. You the player are just flipping the book back to a chapter you skipped over earlier.