It's because Disney has set up their experience as a stressful, dog-eat-dog "vacation" with Genie+ and the crazy crowds this year. Just like you have to be on your phone at 7:00 am or risk not getting on RotR, people are terrified that if they don't get their Halloween tickets (or anything else) the moment they're available, they'll be out of luck.
This is precisely it. When dining reservations, lightning lanes, virtual queues and everything else goes in seconds it creates a mentality that everything will be scarce. It’s part of the overall terrible experience they’re turning the whole thing into.