Some people apparently don't understand what it means to be in a raiding guild. Yesterday, we departed ways with a certain priest, which I will leave nameless because his name is pointless in the context of the situation. Most raiding guilds have minimum attendance requirements, these are put in place so that the group of raiders get used to one another. Therefore they can learn to play off one another. This also helps the raid leader tune strats for the group because he knows his raid. Most raiding guilds assume if you are online you are on to raid. Not on to level an alt or do battlegrounds for that honor you are missing for whatever reason. Most raiding guilds assume that you have some grasp of the fights you are going to participate in, and of course basic common sense. Standing in fire doesn't give haste and being puked on doesn't reduce your aggro.
These things can all be fixed in many ways. I am the kind of person that will give someone the benefit of the doubt once maybe even twice if I am in a good mood. Repeating the above is just something I am not going to stand for. In a raiding guild you have others depending on you and no one wants you messing it up for them. Be it wiping or you are missing an element of the raid because you were supposed to be on. I have said many times this isn't for everyone. There is also plenty of guilds you can join where doing these things would never be an issue.
Let us now go over the worst thing that can happen when you are addressed for these things. Snapping like the world is coming to an end is really not the best course of action. You not only insult the guild, but you make yourself look like nothing more than someone only capable of attaining the rank "Tickle Me Emo".
Think of this as free advice from someone who has dealt with thousands of people in WoW about every which thing. Good Luck at finishing your lockouts.