Commerce on the Internet has come to rely almost exclusively on financial institutions serving as trusted third parties to process electronic payments. While the system works well enough for most transactions, it still suffers from the inherent weaknesses of the trust based model. Completely non-reversible transactions are not really possible, since financial institutions cannot avoid mediating disputes. **The cost of mediation increases transaction costs, limiting the minimum practical transaction size and cutting off the possibility for small casual transactions**, and there is a broader cost in the loss of ability to make non-reversible payments for non- reversible services.

Right in the introduction to the whitepaper.

Maybe you should start with reading it so you would see where things went wrong.