The simplicity of this answer speaks very loud. Kudos to YC. All others should listen closely, and try to emulate it.
The first entry explains the difference between Equity Funding(Give $x for y%) which you refer, and a Convertible Debt Note (can function just like a bank loan) which is what I reference. The second entry is specific to YC's Convertible Debt Note terms, but did not address my question.
It's something to be aware of, but not something that changes the fundamental nature of convertible note financing. Don't sign personal guarantees.
My question was more along the lines of, does anyone in the "real world" of startup financing ask for personal guarantees? Where is this actually happening?