You just got really unfortunate and got a bad group. If people are going to pull before the entire alliance gets to the next room, they have no room to bitch about how hard the fights are without the people that didn't make it in. LotA has a minimum item level of 50, so there's no reason for them to kick you because of your gear. The content is so faceroll anymore that it isn't even funny. As a healer, there's not too much you need to worry about aside from keeping your alliance members alive. Know who your main tank is. Heal your alliance's pot at Thanatos. Four people need to stay on each platform at Atomos. Hide behind comets when King Behemoth casts Ecliptic Meteor. Run back to your alliance's platform when Phlegethon casts Ancient Flare (right after Iron Claws spawn).