Being a healer in FL is still very much about protecting and saving your party members, but you have to do it differently. It's not as simple as it was about. In fact, healers are one of the best ways to defend against the current DRK/DRg meta that has taken over FL.
WHM - Aqua veil is your friend and the difference between a person getting caught by a group or not. Also, Seraph striking a DRK that is pulling your alliance will help them. They all get protect as well as you healing them from some of the damage they are taking. That is often enough to get most people out alive. People really dont understand how much the DRK/DRG strat hinges on player error. Not healing or guarding in time or having just enough HP to survive matters. LBing a group as the DRK pulls also delays some of the follow up burst and scares off some people as well. Everything helps.
SCH - Even easier in this regard. A spread shield and a spread bio will reduce the DRK/DRG meta strats by a ton. Movement boost allows people more escape while using skills. Summoning Seraph and the follow up sheilds are a huge boon to surviving the stack. I've saved entire parties with it.
AST - Again, a great defender. While the Bole is more targeted, AST LB is a huge 30% dmg reduction. it effectively neuters the DRK/DRG combo (which usually has an AST alongside them for the 30% dmg up). Deleting a whole third of the incoming damage is a HUGE deal and should be used well. Not to mention the popped Macrocosmos that will heal a significant amount of HP between dmg bursts.
SGE - straight up annihilates the DRK/DRG combo. In fact, when I play SGE, I had the alliance that did it specifically target me before they unleashed it because I completely ruined their stack combo so many times. Just drop LB on the area the DRK uses it's pull and watch how many LBs and attacks are wasted doing literally 0 damage. It is insane and hilarious. Not to mention popping panhaima to add on t the defensiveness.
So yes, a healer is still very much very strong in FL, but the skill needed to use one has changed. It is no longer reactionary. You cant see that someone needs help and bail them out. You have to be preeptive. If you see a DRK shield up and run toward your group, you know a pull is coming. If you see a but of DRGs jump into the air, you know what is coming. If you see that AST pop LB early, you know what is coming and have to plan accordingly. It's how you become an effective FL healer. You are the one keeping an eye out for that kind of thing. Stop trying to save the one guy getting CC'd to death while being mobbed by 20 people. You aren't going to save them.