Honest question about ladders and rooftops.

So I’ve mostly avoided Assault since launch because their class special is such trash. I’ve occasionally used the Assault for the beacon for my squad mostly. 

Messing around on an empty Cairo server on Portal today and holy crap! It’s so easy to access rooftops without any superhuman feats or without terrain glitching  via the ladder. 

 Anyone with a ladder can easily access these rooftop areas by simply placing the ladder twice.  Anyone can counter these rooftop enemies via a ladder of their own. 

Is this working as intended? Is this a bannable offense? 

If this is bannable, Why is it okay to access rooftops and 2nd or 3rd story buildings via only the ladder on some maps and not others?