That's really all that happened here. HQ Trivia had a novelty value that eventually went away. Losing Scott probably didn't help. Just like Alex Trebek is probably a big part of the reason for Jeopardy's longevity, I think Scott was a big part of the reason for HQ Trivia's popularity.
[1]: https://theoutline.com/post/2517/is-hq-trivia-holding-its-ho...