Except we, you know, ACTUALLY WENT TO THE SHADOWLANDS and saw them for ourselves.
Reminds me of a time someone asked me if I'd still be an atheist if I lived in D&D. No... in a world where a god literally comes down and shakes your hand, things work differently.
We've SEEN things happen. We've BEEN there. We've met Naaru, we've even seen Elune come down and do shit. Many of the gods and demigods of WoW's mythology WE HAVE MET.
We've seen one of the greatest champions of the Light in the Shadowlands, and we've seen what happens to plenty of other paladins, too. Does that mean there ISN'T some Light-specific afterlife? No. Blizzard can write whatever the fuck they want. What we DO know is the Light messed with the Shadowlands, and was NOT welcome there. It's a different cosmic force, so whatever it's doing is most likely fucking with things, just like the Naaru always do.