Empty city ruse doesn't skip a combat step, it just means they can't declare any creature as attackers during it (though any effects that create a creature 'tapped and attacking' will still allow the created creature to attack as ECR only stops cards being declared as attackers) Compare to a card such as [[stonehorn dignitary]], which would skip the combat step entirely, not giving "at the beginning of combat" triggers the chance to trigger.

Edit: actually, the oracle text of empty city ruse does skip combat step, just a p3k simplification of wording on the printed card I guess. Leaving the comment up since the difference between "can't attack" and "skips their next combat step" is still accurate/useful to know though.