With fire resist and two greater fire protection pots you shouldn't need much healing on Vael.
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Mechanically, sure. Here's the thing, though. Mechanic difficulty doesn't mean shit because anyone can watch a Tankspot guide and follow the script when the boss does the same spells it always does.Vaelastrazs was easier than a modern day LFR boss. People struggled because of threat issues and the fact that it was hard to have 4 or 5 tanks use their brains. And if Flamegor was a cockblock, your raid team was just incompetent.
Again, people need to get it through their thick skulls - in terms of difficulty, Vanilla raiding is an absolute joke compared to today. LFR Kil'Jaeden is harder than any boss in MC or BWL
Gearing and focusing 40 people is far more difficult than learning the few movements you need to do in your fancy Legion raids.