Because I can tell you the exact moment that I stopped caring about the Demon. It was at the Royal Rumble when Finn fought Lesnar for the Universal Championship... and he came out as himself.
Yup, the same Demon that emerged to fight Baron F. Corbin at Summerslam and Bobby Lashley on Sunday, but not BROCK motherfucking LESNAR when the UNIVERSAL TITLE was on the line. It made no sense, and it completely took me out of the match. Was still a good match, but took me a while to get into it.
How do you even spin this in kayfabe? If Balor has no control over when the Demon emerges, the Demon should still have the common sense to realize it's a big ass match and its presence is needed. If this thought did not occur to it, can we then assume that the Demon is mentally retarded? That's certainly not helping its cause. Was it occupied with something more important? Which in turn raises the question of what exactly the Demon does in its spare time when not possessing Balor. Considering that it only has control over a physical body when it controls Balor, I fail to see how it can do anything particularly important, like go to a doctor's appointment or a strip club, for example. Again, not helping its cause!
It's so obvious that they want to protect the Demon, because it's undefeated on the main roster. But they still wanted to do Balor vs Lesnar, without having Balor go over. And they still want to cart out the Demon as a "special attraction" for shows like Wrestlemania and Summerslam, even though the audience has now seen that it didn't come out for the biggest match of Finn's life. You can't have it all ways, WWE.
When Lesnar attacked Balor after the match, I was certain that they were gonna build to a Balor vs Lesnar rematch at the next PPV with the Demon being involved this time around. That would've made sense. But it went nowhere and Lesnar didn't compete again until Wrestlemania, and now he has presumably gone back to UFC. I kinda wish we got that match instead of Lesnar vs Rollins.