Yakra at http://mirrorshield.blogspot.com/ describes his first hand experience how a Raid Leader/MT who has grabbed all Tank gear only to disappear on them, causing the guild's progression to hurt.
I had the same experience, actually happened twice ... I came back from deployment around May 2006, I left when the guild was learning Razorgore and came back with BWL cleared and up to Princess Huhuran in AQ.
The guild's MT then went MIA. He's actually the 2nd one to do that. So here I am with my Tier 1 8/8 trying to tank BWL and AQ /sigh.
They promoted me to OT quickly and passed all the tanking loot to me. The substitute MT then wanted me to gear up cause he doesn't really want to tank, he wants to DPS.
I got promoted to MT, got Tier 2 8/8 and was ready to tank Twin emps in such a short amount of time. In the end we got server first on Twin emps and 2nd on Cthun.
The guild didn't give up on gearing up the MT despite the bad experience. We understood that when going for server first your tank needs to be really geared. After killing Twin Emps for the first time the loot just started to drop from there =) which means happy raiders.
My thoughts on MT Priority:
First of all Momarr(See Yakras post) made a mistake of not delegating tanking. Bad bad bad bad.
Instead of me saying MT priority is the way to go. I'll just discuss why it works for us =).
For a hardcore raiding guild who is aiming for quick progression. Gearing up your Main tank will be the first priority, always is and always have been if your goal is to be the first in server or at least one of the first ones to clear content.
Why does it work for us?
a.) 99% of the time we know the player we are giving loot to for months if not years. I've been raiding with some of these guys since 2005 pre BC.
b.) The people in the guild has a common resolve. They all agree(or at least looks like) that we want quick progression.
Clearing content faster = more gear for everyone right at the start.
c.) Being #1 guild in the server makes people not jump ship and brings in alot more competition between raiding spots. Though this is not really an issue tanking spot wise.
d.) Tier Token makes it much easier to gear up a new tank wherein back in the day you have to wait for that one specific drop /wrist.
e.) Our MT is the GM who is on all the time. And I mean literally.
f.) Cause we are Min-Maxers =). Gotta get our MT the best possible stats to help out healers. We have our fair share of 1-2% wipes because healers went OOM at about 8-10%.
Eliminating Tank dieng cause of bad gear is always good for us. Which leaves positioning, right strats, more dps left to tackle to get that first kill.
A good example is how we handled Wrath's 25 Mans.
Tank loot went to the GM/MT. He did pass on loot that are minimal upgrade to the offtank. At the same time we geared up our 3rd tank druid but all the major upgrades still goes to the MT. So in reality we didn't just gear up 1 tank, we geared up 3 in a span of 1-2 weeks with MT having priority. This was done mainly because of Patchwerk ...
After doing 2 weeks of Naxx the Tank priority loot has been lifted in our guild. MT priority will come back once Ulduar instances becomes active. Which I think nobody really mind. Hey like I said the faster we clear the next 25man the faster others get loot.
Back in BT we did gear up a new tank who joined only to go POOF on us. It really didn't hurt us because the GM or me just had to respec to tank. Of course GM was pissed =) and so did I but hey shit happens.
Like last night I MTed 25man Naxx but I passed all the tanking loot to the would be MT for Group 2 next week. Did I want the tanking loot? Hell yeah but Tanking is not my main spec .. Herc wants DPS loot! Gimme!
The tank loot that dropped was: bracers, best tanking weapon, best tanking sword, t7.5 helm, legs, bets tanking boots and I already forgot the rest.
All these went to the OT last night. So next week they won't be needing me anymore =P. I just helped out this week and showed how to do things(tank!) to the OT. I know he's more than ready next week. I did my role and next week I'll be back to dps. Those loot will drop again but again securing Group 2's naxx is more important atm.
Guilds have cleared endgame bosses w/o having the rule MT priority of course.
MT priority though when done right can save your raid some wipes and hey maybe even a week or 2 early kill on a boss. Everyone needs to be on the same page and the raid has to trust the MT.