Not sure if you're asking a serious question about MSF but it's interesting anyways - when these types of orgs are fundraising for a specific campaign, say Darf

Not sure if you're asking a serious question about MSF but it's interesting anyways - when these types of orgs are fundraising for a specific campaign, say Darfur, then they can NOT use that money for any other campaign, say for ex Turkey earthquake. That's why they'll sometimes tell you to stop donating. That's here in EU at least (source is a relative who volunteers for such an org).