My honest opinion on this is that you were in the wrong. The comments and responses you received telling you to "F off" were unacceptable and completely inexcusable and no amount of frustration on those players' parts can take that away. However, that being said, you should have known those fights if you expected to participate in them. My philosophy on raiding may be unpopular with people who do not do progression, but I feel that it is the best approach whether you are doing SM, HM, or NiM. The most important thing that a person can and should take into an operation, regardless of difficulty, is knowledge. These are general statements, so not all will apply to the OP, but with the amount of GF I have done in this game, these are my gripes with a certain portion of the players.
You should know your class. I don't expect you to know your rotation perfectly, and to execute it so that you can beat HM enrage timers in SM, but you should understand how to play it, be you tank, healer, or dps. You should also know all of the fights for every operation you plan on doing. I understand this is a lot of information as there are 9 operations with 3 difficulty modes and 46 bosses. However, no matter what interests you, be that be becoming a better player, being a good member of the community, or just having a good time and enjoying the content that this game offers, it is essential that you know what you are getting into when you enter an operation. Knowing a fight perfectly without having experienced it is pretty much impossible. However, you should know what to look for when you start a fight.
I think this where a lot of players don't understand how GF works in reality as opposed to ideally. GF is not a place to learn. GF is a place to do an operation quickly so as to get gear, either for alts or mains, and for some to just enjoy the content. But when doing a GF, people expect it to go quickly. None of these things happen when someone doesn't carry their weight, and it always comes down to knowledge, either of the fight, their class, or both.
So I will admit that I don't give in depth explanations of fights if they are asked for. I will often say don't stand in this or that, and if there is a mechanic that the person must do, then i explain it. But it is frustrating when you go into an operation knowing what you need to know, and other people don't. To me it is discourteous, but as I have said I am someone who enjoys progression raiding, and I am sure there are many who would disagree with me. That is enough of my 2 cents though, and I am sorry you ran into elitist ******es instead of just plain elitists because there is a difference.