Blizzard did a great thing in WoD with the cross-realm raid tool. Now people who don't have guilds, who are on tiny servers, or who cannot plan around a set raid time can finally participate fully in endgame content....
... unless you are a hardmode raider. In which case, LOL! Why? FYTW.
In previous expansions (I skipped Furries of Chinaland) I did and cleared all the hard raids I set my mind to. Ulduar hardmodes (best raid ever). ICC25 heroic. Quit for a while, returned in Cata and did Heroic FL and Heroic DragonSoul.
And I did ALL of these hardmode raids in pug groups!. I put in the time and effort to form pugs formed of competent players from my server community and it paid off for all of us with clearing the cutting edge content.