Have you seen the size of my dongle

Electrocoin stuff requires a dongle I believe, question is, why?  I mean why at the time the machines were released put a dongle on, which I presume is just a few wires connected up to each other, like a SKY card?

I get it that it was there to be some sort of protection, to stop clones possibly?  

But we're talking the 80's, not 2015/16 and something uncrackable like fifa16 on the PC.

Can anyone explain it?

Cheers,

NQ