1. Counterparty risk cannot be eliminated, only reduced. The only counterparty with zero risk is a government, which can print more currency if supply is insufficient, devaluing everyone else's currency.

2. Exchanges do go down, the only question is how often. If the exchange does go down, you want the exchange to say, "We're doing our best, but volume has exceeded our capacity. We'll be up as soon as we can." The alternative is to continue to accept trades and pretend that everything is okay. Honesty is good.