The problem is the term 'manipulation' can be easily misconstruded into the whole BGS and player factions thing, because it requires Dev involvement to 'manipulate' the BGS and put these factions in place in the first instance.
Someone who does Powerplay more than me can probably quantify it better but, for example the Dev's put a player faction into a system as the controlling Power once which (i) backed a different superpower than the previous one and (ii) was a different government type, messing with the PP fortification costs for that system for Sirius (who controlled the system in terms of Powerplay).
The powerplayers had no way to oppose this sudden appearance beyond a long hard slog at the BGS to set things right, which if done using ingame mechanics rather than the 12 year old dungeon mastering that seems to happen, would have been interesting.
Fair points, Goose. The BGS is certainly not perfect, and mistakes have been made, but as we learn more about it, those who choose to play it are becoming ever more adept.