I still feel like people downplay Universal's efforts to procure IP. You can't just snap your fingers and get one in 2025, even for something "niche" like the Grudge or the Ring. In fact, it's often harder to get those than it is to get something bigger. And KKFOS and Trick R Treat aren't even fair comparisons because the rights-holders pass out those licenses like candy -- there's merch of pretty every much every variety, everywhere. That's less true for something like The Ring, or whatever property matches the criteria you have here.
You also hear people talk a lot about Six Flags, like "how were they able to get Stranger Things, Universal already had that deal" or like "Why not get NOES again, Universal already had that deal," and boom, you just answered your own question in the asking -- they already had that deal. None of these things are in perpetuity, for starters, and there are also what basically amount to competition clauses in a lot of these agreements. It does not behoove a rights-holder to work with the same third-party over and over again.
TL;DR, this process is a lot more complicated than people understand and I don't think it has anything to do with HHN changing how they operate. It's the other way around.