The “pass” is definitely contributory, but there are many factors at play. Social media marketing, better access via increased flights and origins, built out accommodations at village, more dining options, and perhaps most important - more terrain for intermediates (think all that stuff around Casper). Marketing is geared to Momma bear, momma bear likes these things. <- sorry, that is a broad generalization and doesn’t reflect views of all “momma bears”, but still true.
I think this plays a big part. I was just in JH a few weeks ago and you couldn't walk 10 feet without some sign or piece of literature blasting at you "JACKSON HOLE HAS GREAT INTERMEDIATE TERRAIN NOW, NOT JUST AN EXPERT MOUNTAIN!!!!".
From skiing around and overhearing people chat it definitely sounded like a large part of those crowds (the weekend after MLK weekend, very busy) was exactly that demographic.