Ask HN: Does Bitcoin solve the micropayment problem?

Is it possible to do micropayments with Bitcoin? There are many contradictory information about this. I am interested in payments like at a grocery store. Say, $0.5 to $20.

You can't do this directly on the blockchain because it is too much overhead, too slow and too expensive, right?

There are "micropayment channels" for repeated micro-payments (i.e. pay for API calls), but they are not intended to be used for one-time payments, right?

Though you can build one-time payments on top of payment channels, by involving a third-party middleman, right?

This breaks most of the decentralized awesomeness of bitcoin, right?

Are there any altcoins that actually solve the micropayment problem?