An even shorter, and more glib, summary can be: "Don't put all your eggs in one basket." The more control you give one entity over anything at all related to

An even shorter, and more glib, summary can be: "Don't put all your eggs in one basket." The more control you give one entity over anything at all related to your livelihood, the more likely that something going wrong (through malice, ignorance, or just "bad luck") with that one entity is going to have catastrophic circumstances.