Roll Back iOS Update before next general update is released should not be impossible and yet its seems it is. Anyone have anything to add?

I have several were used for beta and I’m no longer using them anymore so I would like to roll back to the original firmware after a complete DFU is executed. But I seem to be running into a problem as to returning back to the current or previous iOS version. Everything I’ve read so far has informed me that I need to wait until the next public update is available and download that in order to bring it out of beta testing category. This just seems unacceptable in the sense that there is no logical explanation as to why anyone would have to wait For the next update in order to roll it back. As I always say where there’s a will there’s a way so let’s figure this one out.