Hi, we could have implemented this using a smart contract, but explained some reasons why we didn't in our news section:

• Any user who can send money from their account can use it (supports Scatter, Greymass and the Command-line Wallet)
• This does not consume any account RAM, so there are no unexpected costs.
• This tiny micro-payment reduces possible spam, and will hopefully allow us to maintain a high quality profile list.
• Speed of deployment. We can provide a useful service more quickly this way. I am currently only partially familiar with smart contract development.

https://labs.eostitan.com/#/news