Tax reasons, and liability shield.
I've done taxes for a lot of doomsday cults. They never listen.* The ones that succeed, do so because they work for their own cause, not the IRS.
Remember Y2K? Wound up being a big nothingburger because the end-of-the-world cult insisted on a general partnership (which is to say refused to use any corporate structure at all). Aside from wasting money paying taxes at the 28-35% personal rates and being unable to take deductions, there were several lawsuits where every cult member was held personally liable with no limits - they lost their houses, which were built directly on the ley line intersections. Ugh! Basements full of carefully aligned crystals, all wrecked when the plaintiff prepared the houses for resale.
A proper corporate structure could have delayed the creditors and IRS until after January 1, 2000, when it wouldn't have mattered. which would suffice obviously.
Contrast with The Global Warming Initiative LLC. Operative word LLC. It's just crazy. Aside from the tax situation really working well, the real eye-opener was that nobody questioned what they were doing. People just assumed if a corporate entity does it, it can't be pure evil. (and yet they own a cell phone. How can this be?)
Yes, there were lawsuits against individual Members. And some of them won. But the LLC was manager managed, so all they could get was charging orders, which means they take profits ahead of Members if the Manager ever chooses to distribute profits, which of course he never did. The LLC went bust, but not before all the coal plants and freon factories were built. Mission accomplished.
Bottom line, a good corporate structure is the difference between success and failure. Be like the Lower Manhattan Beautification Committee, not like the Branch Davidians. Seriously, do you see where BATF shock troops have the NRA headquarters surrounded and under siege? No, you do not see that siege? There's a reason for that!