Basically capabilities make with a EnergySystem Processor like IC2 has it no sense at all. It actually makes the System slower,
more complex, and more likely to break. Since its a Global Manager that handles everything about EU.
RFBased Systems dont work that way. Each individual part in a RF System processes its own little thing, which is actually more havy then a Global manager. Even if the Global manager is poorly written...
Its overall less to process, more stable and has a lot of upsides to it. I am wondering why RF is not using one for their system. Because RF would benefit more then EU out of a Global Manager System.
But yeah capabilities would bring in only more instability thats all what it provides, nothing based of Uniqe freedome, its actually less freedom for the person who handles the EnergySystem and is not a user of the build System...
And the User can use a Interface the same as a Capability. Forge even adds systems that allow you to make interfaces more worth then Capabilities.