I see portage "etiquette" about the same as the rules of driving a motor vehicle.
Common sense dictates you let faster moving "vehicles" pass you and you keep to "right" to keep the "lane" clear.

But we all know rudeness/lack of common sense is everywhere and depending on how bad the situation is and the response when I ask to "play thru". If I see the party are Newbies, I try and help them out.
IF I see they know better but don't give a damn, I politely ask them to open a thru lane and if that doesn't get a decent response, I rip them a new one ;) ;D