Agreed. 
Those registered to vote, but didn't, plus those not even registered to vote are larger than the Tory and Labour vote put together.

The Uni Party / Oligarch worst nightmare is  seeing these people becoming engaged and voting for a party away from Red and Blue.

Hence, I've a sneaking feeling that behind the scenes they promote "It's cool to check out of the syatem" to ensure they don't realise their voting power.