I do believe that this "monitoring of inventory" is a de-facto, unpublished devaluation of the program.
I concur that it is nearly impossible to get the seats that you want on overseas routings, without massive amount of reroutes, or restricting your trip to specific cities.
I don't think that it was all the US DM Maximizers that were ruining this for everyone - costs and other program devalations are happening everywhere - across all airline alliances.
This is the generation of spending more and getting less - it's happening everywhere across Star Alliance, to the gas station to the services you get from your city council.
The flying of 15 years ago was fabulous. It is no more.