Does everyone state times an hour earlier than they want to correct for this rule? Is this just time for the party's hosts to perform a certain function? ( Punctuality is heavily engrained in me, and I can't understand the point of a time if its to be disregarded as a matter of policy )

I experienced this in Sweden. A Indian colleague was having a party for family and friends at x hours. I showed up fifteen minute early and most guest arrived 1-2 hours later...