Well, it is considered soft because the party that offers the service won't know your identity unless they take action (which they can easily can). There's an extra step for them to get to you. Your bank has the KYC, and the does not, but there's a very easy step to fully identify you if required.

I see more like: I can kill you, or I can break your spine and put you on a wheelchair. Soft KYC is the wheelchair option. 

 They have everything on the bank statement. The only missing thing is a smily photo with the date on a paper.