There's also a significant niche of people who want assurance that a transaction can never be reversed. For example online entertainers who get donations for thousands of dollars only to have them charged back months later.

it is possible if you choose to use a third party.

The good thing is that you don't have too! You are not forced. If I send money to a friend or familiy, I don't need a third party.

A third party could be either a bigger financial company or just a trusted third party in a specific domain both people trust (and make a 2 out of 3 multi-sig with it, and if I get delivered what I want and the other side receives the payment, the payment processor has nothing to do, but could in case there is a dispute)