Just skimming through this thread...it all seems anecdotal. I would be interested in real data about number of skiers, pass holders, etc. as well as numbers related to holiday periods, weather, and conditions.
Warning . . . data and history geek thinking below.
In terms of snow conditions, it's possible to get historical data for the last 10-20 years for specific resorts. However, another factor that is harder to quantify is the marketing reach that the multi-resort passes provide in the age of social media and smartphones. Who knew about the first Epic pass in 2008? How did people learn about it's existence? Did those who were season pass holders at the three midwest ski resorts bought by Vail have any idea about the Epic pass at the time of the purchases? Were there NY Times or Washington Post or Bloomberg articles about Epic in 2008?
It took a few years for the Mountain Collective Pass to get the word out after the first season (2012-13, 4 destinations). Same for the Intrawest Passport that evolved into the Max Pass, which went away after Alterra came onto the ski industry scene.
What's also unknown as hard numbers is the data for the ski resorts that compete directly with the destination resorts in a given region. Presumably the number of people on the slopes has been higher this season where it's been snowing steadily all winter. I heard someone knowledgeable about Waterville Valley (involved with set up for the major race events) say that there has been the longest period of good snow conditions in recent weeks than he can remember in a long time. On Wed, March 13, there were over 15 quad chairs that loaded right after opening at 9:00. Granted, some of those eager folks were part of the senior club but there were people of all ages throughout the day.