We've all been there... People want something to blame for losing, and you stand out. Nothing more to it.

I got plenty of hate even during the pre-patch where I was steam rolling BGs as 5x Ret consistantly being the top 4-5 chars on killing blows (and having very few deaths) and usually most bases taken on the lead toon. Even then, it was always my fault if the team lost. The peeps with no gear, AFKing, not fighting anywhere near bases had nothing to do with it. Nope, it was the one organized, efficient group on the team that made them lose.

While there is ground to multiboxing sometimes not being not very effective for playing objectives, I still wouldn't concern myself too much with people in /BG... If they really really care about BGs that much, it just goes to show how little else they do outside of them, meaning they are most likely clueless. Infact, I've made a habit of inspecting the biggest whiners in /BG while playing single toons and consistantly they are people with 0 experience in constructed PVP.