I agree with the notion that NPCs do not effect the BGS. They are there for our benefit only. When we quit the game, they all vanish. Think of them as a movie set town. When the cameras stop, one look on the other side of those buildings reveal nothing but that forward facing facade.
As for the hate towards SOLO and solo players... The argument that solo players screw up the BGS is nothing but a Red Herring. They use that silly claim to disguise the true motivation behind these people's gripe. Some people just can't stand the thought of anyone not sharing their own notions of what this game is, and how it should be played. These are often the same folks that have issues with those who don't want to play PvP and prefer PvE only.
Ever heard the term "My Way or the Highway" ? Well... That is who you are dealing with, so good luck with that!
I find it very telling that you never see solo and PvE players making these kinds of comments towards PvP players and demanding that OPEN play be closed down. Perhaps we are content and confident in our choices, while they worry that their supply of human cannon fodder might eventually run dry. This line of thinking also leads to intolerance towards any other viewpoint, and they need everyone to agree with them and their choices regardless. Do you see any similarities between the "Kill Solo" crowd and religious zealots? I do.
Personally, I just ignore the noise from this group these days. I will play this game the way I like to play it, and I could care less if anyone else has a problem with that.
I play 100% in SOLO and what I do has no real impact on anyone else in the game. I also could care less how anyone else plays the game as long as that play does not negatively impact others without those other player's consent.