I can somewhat understand this. If you're part of a big guild, and that guild is putting together a pug run with it's members, there are going to be people getting carried, and people doing the carrying. Everyone expects that, especially the players doing the carrying. But when you're trying to join a progression group, playing a weak class means that the other 3 dps are going to be carrying you. All. The. Time. It's totally fair to ask other people to carry you for a pug run. It's not at all fair to ask them to you carry you twice a week for the foreseeable future.