PSA Vendors are not using bitcoin as currency if they receive payment in USD

I'm agnostic to the future of bitcoin as a currency, but many of the posts here are very misleading. Of course a vendor will "accept bitcoins" if they are getting paid dollars. If they're not getting paid bitcoins all they're really saying is we don't care how you come about your dollars as long as they get them. The current system is no different than a hypothetical system that immediately changes oil contracts, gold, stocks, or poker chips for cash and allows you to buy things with that cash.

As for the whole irreversible thing with a low transaction cost, that's a feature of the application. It's not inherent to the currency.