I am just me, not a Church leader, but I think it is for several reasons: 1) prophetically-encouraged preparedness, like in the days of Noah (food storage, avoiding debt, save for a rainy day, etc), 2) to best be able, long-term, to fulfill the divinely appointed mission of the Church to spread the teachings and voluntary systems that bring peace in this life and eternal life in the world to come.

I have collected a bunch of links (official and not) w/ further info, at my personal site, such as at: http://lukecall.net/e-9223372036854578831.html

and http://lukecall.net/e-9223372036854589754.html

and my own thoughts on this and various subjects at http://lukecall.net , such as http://lukecall.net/e-9223372036854587122.html .

ps: It strikes me after many years of general reading & observation that economic up/down cycles would be very reduced or different if we used savings instead of debt, more. And, being in debt leaves one under the control of others, to some degree, reducing independence of planning and action. I'm not saying it is never appropriate, but it also has some somewhat predictable effects.

Edit: I see that others have also posted these links that give some official responses:

https://newsroom.churchofjesuschrist.org/article/church-fina...

https://newsroom.churchofjesuschrist.org/article/first-presi...