If you'd have taken out the Dealer those Etd would have had significantly less of a lead, if any at all.
They were still more Cath than Cath was, though. And yes, everyone saw Cath suckage coming.
And to stay on topic - no, just no.
It will give big EMP planets an even bigger advantage, and smaller ones won't benefit from it much since they'd have to lose ships in order to disable a measly 5%.