It seems like after a while, tech rules become one band-aid on top of another band-aid on top of........ the sanctioning bodies do the best they can trying to keep the "innovators" reeled in. But.........
It's always been that way. As an engine builder, you are always looking to get the most out of the rules as you can for your paying customers -- that's your job.
As a tech man, it's to keep those gray areas and loop holes from being exploited.
The best set of rules I've seen is the LO206, which were written by the manufacturer of the engine, not after the fact.
As long as the manufacturer keeps their production units withing their own guidelines, then it limits the ability of the "creative development department" at engine shops from using too much of their handywork.
Even the 206 has had clarifications and minor spec changes over the years.