wouldn't they also greatly reduce the inventor's chances of ever making any money with their patent?

Maybe, maybe not. If the inventor wants to make money by implementing their invention, and also benefit from the ideas other people have and implement which are similar, then this would help them. If they also happen to believe that exerting most software patents are akin to extortion, and they have no interest in it, then no also.

And if you can't make any money with your patent, why make a patent? It's costly and complicated. Might as well just publicly disclose the invention (in a legally acceptable way), and the result will be the same as filing a patent under DPL.

It's generally less costly to patent something than defend a patent suit based on prior art. For example, see the podcast patent fiasco. Plenty of prior art, millions of dollars to defend.