I think the flaw in your arguments is that the game is currently balanced around the overabundant tools (exploits) that you claim we can ignore.
You may not mind how I approach the gith fight, but the fact that I will die a horrible death unless I use my foreknowledge of what is going to happen to position myself where I need to be, shove everyone and shoot them down from high ground kinda limits my options.
I claim you can ignore Barrels ... and since bo barrel was mentioned in your example, i would dare to say we agree on this one.
If you want to talk about any other non-PnP rule in game, please move to relevant topic.
All i can say is that you can position your characters even without foreknowlege (at least i did on my first play ... and i dare to claim that i didnt have any foreknowledge back then
) ... and even if you dont, some people (not me tho, i didnt try this yet) claimed that even on Patch 5 they are killable even if your whole group gets down to talk to them. So, i believe it is possible.
