Bitcoin just kind of flips the problem, it doesn't solve it. In a world where payments can easily be reversed, sellers take on all the risk. In a world where they can't be, buyers take all the risk.
You can get pretty far with a reputation system, and in a market with many more buyers than sellers it's nice that now only the seller's reputation matters. But for a lot of people there's still benefit in having a trusted middleman like Paypal.
Technically, but not legally.
Transfers are 100% reversible by going to court, so Bitcoin is really only non-reversible for criminal activity (dealing drugs, gambling, etc) where someone cannot bring an action because the contract was illegal in the first place.
This technical non-repudiability is a feature that only works for criminals and is an anti-feature for legitimate users.
Of course, the huge dark side to that is that there's now a way to easily send money in a way you cannot reverse. This provides a huge incentive for things like kidnappers demanding their ransom in bitcoin. It's often valuable to be physically incapable of doing things.
I'm long-run bearish on Bitcoin because of this analysis - the majority of its value is in something that makes governments and other coordination mechanisms interested in destroying it.