The minor races are not allowed to accumulate ip but they still build influence starbases all over.
The minor races never colonize planets but they build colony ships.
The minor races never invade but they waste time building troop transports.
The minor races cannot be spied upon (heaven forbid we waste an agent) so the only way to see what is on their planet is to invade.
After their initial attacks, the peacekeepers just sit and drool.
I'm sure I've missed a bit.