For me, the journey is at least equally important, if not more so. People would go on forums and talk about what it could be.

You’re right, that’s arguably the main reason why these shows are so popular. People love trying to work out the mystery ahead of the final reveal and, compared to more conventional mystery formulas, mystery box gives them so much to work with. You see a lot of creativity in the wild theories fans come up and no one is wrong until the very end. That does mean the ending is super important to the overall reception of the show as a finished product, though. Like I think the journey can be the bit you remember fondly if the ending was sufficient, but if it’s underwhelming then it just all feels like a massive waste of time - at least for me.