For years, doctors only had 3 main alternatives when it came time to get paid the non-insurance portion of patient bills. One alternative was to collect full cash up front. Unfortunately many patients simply can't afford to do that, so they postpone treatment or go elsewhere.
The second alternative was to collect as much as possible up front, then send a bill to the patient and wait to get paid. Since paying the doctor is often not at the top of the monthly bill paying priority list, the practice often ends up either getting paid very late or in many cases, not at all.
The last alternative has always been outside patient financing. However, there are two main drawbacks to this option. First, the patient may not be able to be approved (even though they may be very able to pay). Second, if the patient IS approved, either the patient has to pay an exorbitant interest rate or the practice has to give away part of its services (in the form of a "discount" factor).