The point about strafing was to illustrate the kind of players that exist on a private server. Most of them are completely oblivious on how to avoid mechanics or cheese a fight. I'm safe to affirm that you haven't done any kind of progression when the content was originally released or relevant, otherwise, you wouldn't state that discipline priests are "mandatory". Discipline priests, while multiple guilds were still trying to obtain their Light of Dawn progression (without the raid debuff), were barely used for the whole raid, in fact, they only became so popular thanks to the Lich King encounter (Infest turned them into a "must" while doing Icecrown Citadel 25 Heroic). With all things considered, you're only able to state that a discipline priest is mandatory in a raid if you're playing with worthless players. I'm sure that you'll eventually understand that if you have a strong restoration shaman or a strong restoration druid you'll always see your raid properly covered in terms of hp/s and with a proper healing efficiency.
Restoration shamans, actually, outperform restoration druids if properly played. Restoration shamans have more viable solutions when it comes to deliver an urgent AoE heal and, if they're really good, they can snipe heals from almost every single class or spec. Keep in mind, I ain't even considering if they're best in slot or not since that's not required for this specific point.