I am familiar with the process as well.
The reason we don't use it is our desire to work with varied types of steel at varied thickness. Induction heating requires knowing the chemical analysis, the thickness, and then varying the frequency and intensity of the magnetic field to heat the material. Induction also has a tendency to heat only the outermost material as careful consideration has to be applied to thoroughly penetrate the steel. The frequency of the magnetic pulse is of paramount importance...
Induction is also cost prohibitive in both energy and equipment. The magnetic array that is required is not something that is easily put together by the hobbyist, and the power used can vary greatly thus requiring dedicated power for just this one device. In other words, to heat something the size of a knife, reliably and quickly with the ability to rival a gas forge wouldn't be a device you could just plug into the wall.
Think about the high energy used by a welder to heat up both parent material and welding rod in a stick welder. This is not something that is so far separated from induction even though the welder applies heat through a direct application of current, and the induction process from magnetic field manipulation of the material as each have to consider the target material's composition and size.
Induction works well for targeted specific heat in a material, but for what we are after we are seeking a cost effective way to heat any steel we choose to a specified range and then perform a process on it. Then back to the fire and so forth. If the technology ever becomes plug in and then is a cost effective replacement for my forge, I will jump right on board.
Feel free to correct me if that is wrong, but for one it has been two decades since I was around induction heating and I am not an engineer by any means...
