That's true. The only point I would add is that my loan is with the brokerage and they put up cash collateral. I'm not having to deal with individual short sellers and whatever risk profile they might have.
i don't really know of any aside from the brokerage itself going under.
i would imagine brokerages want to make this as low risk as possible as it encourages more transactions, so they can charge more fees. and they also get their cut of the premium.