I agree with what you say, but the question that TFA asks is still relevant, since 'own goals' have always been counted the way they are. So the number of own goals is still higher than usual.
I don't think it's necessarily true they have always counted the way they have even though the "rules" for counting theem have always been the same.
I think the reason is because there is more at stake. Take last night for example. The defender busted a gut to get back to try and cut out the cross, even though the chances of doing so were minimal - the end result being he put it into his own net. In a normal league game the defender would likely have just accepted his team's fate and Sterling would have had an easy tap in.