IMO, all you have to do is take a look at this forum to get a general idea of why there's no Avalanche rally, or any other rally, for that matter.
Total members: 39,817
Members who posted in the past year: 3414
Members who posted in the past month: 598
Members who have never posted: 18,945
Members who posted fewer than 3 times: 26,305
Members who posted fewer than 10 times: 32,154
Members who posted fewer than 100 times: 35,652
These stats are for a "free, all you have to do is log in" type activity.
On April 1, 2018, we started, at the membership's request, a Forum decal program, so that members could order, at a reasonable price, a decal to put on their trailer, so other members of the forum could identify them, on the road or in a campground. Less than 60 members purchased decals.
I'd think that corporations like Keystone, THOR, and many others have realized that investing their profits on the "few people who participate in group activities" is no longer a "money making venture" for the company. They have turned to other ways to invest in building participation rather than spend money on a program that doesn't return increased profits for the company.
Now, it seems they spend their "growth investment budget" on things like free calendars, pens and other trinkets, to give out at RV shows or on sponsoring a RV show at a local dealership, to "grow interest" rather than spend that money on "entertaining a few who have already bought the product"...
ADDED: TomTerrific: You might want to "get the official response" from Keystone as to why they don't sponsor such rallies. You can contact the company at this link:
https://www.keystonerv.com/customer-service . They don't monitor or participate in this forum, so you won't get a response from Keystone here.