you've jumped into the wrong part of my posts my friend. read my earlier ones it already answered that
Edit I have the quote for you* TBC had quests forcing you to clear raids before you could move to the next.
Vanilla/cata/wrath (with the exception of malygos) required no raids before to be cleared before you could clear the next. Only dungeon attunements for some raids.
now the 2nd line heres a bit of info. the main difference between Vanilla and wrath/Cata was that you can get gear from outside raids to help you get into those raids. It mainly helps Alts and players returning to the game and NEW players. If you raid it wont really help you much unless you've got bad luck with drops. Attunements aside from onyxia in vanilla were very simple to get (nax one was a bit of a pain if you didnt have the rep) there were no raid to raid attunements only dungeon to raid attunements in vanilla.
oh and on your sunwell part, you're not entirely right. You could get ZA and badge gear and get enough gear by this point to jump into a TK/SSC guild at the least or if you were lucky enough into a BT guild. if you had raided then you would know (or maybe you forgot :P) Earlier in the expact when the attunements were in place there was no way you could have done that.