Both are important. You can have small number of people skiing a lot. Or large number of people skiing occasionally. I don’t see why one is “more important” than the other.
One may argue one without the other isn’t very useful
Both can be important and yet one can still be more important than the other...
Active participants shows whether there is actual growth in the sport or not (i.e. are we getting new people into the sport). The same number of people skiing more days each isn't true growth (especially if it is more days on a fixed price product like a pass). So pass-holders skiing more days actually dilutes the amount of revenue per skier visit from lift revenue. You can argue that you can make more from ancillary revenue (F&B, rentals, etc)...but that's more variable as not everyone eats on the mountain, etc. Everyone has to have a lift ticket product though... So to say the industry is healthy you ideally want to see an increase in the number of participants. Now of course you also want to see people keep coming back and skiing more than a single day. That's where the skier visits compared to the active participants comes into play to help provide a clearer overall picture.