I do something similar, and I gotta admit, sometimes I do use the Golden Gate as an actual ‘gate’ 
You should do an AMA. I’d be interested to know what compels you to play the game like this.
It’s in the name, Golden Gate
But in all seriousness, I’m not a pro nor a competitive ranked player, and apart from making my city look pretty, playing against AI (which does a lot of interesting behaviors), and every player having their own way of building:
I use it as a sort of a choke point, I similar to a defensive architecture or defensive posturing. I play a lot of defensive civs. Well, I started using the Kremlin more so I don’t have any recent footage of it, but I do something like this with the walls (recent games), if things go well I don’t even full wall it, although it’s a heavy oversight because raids. It’s a very expensive commit if they, while also making resource gathering safer
Note: In AoE2 people have an interesting habit of walling off their city and resources
Note2: This map also helps with that, but I also tend doing that in other maps
Note3: The rus wall is pretty good, it’s also taking advantage of its uniqueness
Note4: The square in the TC is for the imperial farming expansion late game
I have other 2 screenshots if you want to city my city layout, can only post 1 at a time