Its 2 fold.
Sky know they will have a viewing public, due to "most" fans being home or in the pub for the 5.30 games or the 12.30, which in turn increases the money they pay.
And also the Saturday attendances thing, which is more to help the lower league clubs rather than the Premier League.
So whilst the rule that was brought in the 60s is possibly outdated and proven to be utter rubbish, it still impacts on clubs.
It is, in fact, doubtful whether closed periods are capable of encouraging attendance at matches and participation in matches. Both activities have a completely different quality to the following of a live transmission on television. It has not been adequately shown to the Court that the closed periods actually encourage attendance at and participation in matches. Indeed, there is evidence to refute this claim: for example, in an investigation of the closed periods under competition law the Commission found that only 10 of 22 associations had actually adopted a closed period. No closed periods were adopted in France, Germany, Italy and Spain, or in Northern Ireland, that is to say, within the sphere of influence of English football.
Advocate General Kokott of the
European Court of Justice
So the most important thing here is making Sky/BT feel special so they pay the big bucks.