A lot of times people refuse to accept that this is a multiplayer game - and that if you want to progress your character through raids ( and gear ) you have to figure out the best way to team up.
After the whole Giantstalker to Nethergard Keep moving, I signed up for a raid with my priest, mostly on pvp gear, with very little experience as I had been leveling my way healing in battlegrounds – guild-lead laughed about my half-arsed gear, enchanted it all properly ( I had it all properly gemmed, but was leveling enchanting so agility and stamina enchants ftw ) then invited me to the raid and we went to Ulduar… …
It’s not like you can’t solo the game as much as possible, and merc your way through pugs - but you can’t expect to be taken in by people who don’t know you at all, and have their own agenda.