Looking into how the talent trees have formed so far, more raid slots are locked behind utility/buffs than ever before. Whilst I agree with the philosophy of people having cool stuff to bring to the table I’d argue a level of homogenization is healthy to prevent raid compositions from becoming a pure spreadsheet activity.
A typical Mythic Raid composition would have:
2 Tanks.
6 Melee DPS
8 Ranged DPS
4 Healers
Of these slots you have the following to consider:
Raid Buffs:
• Evoker
• Mage
• Warrior
• Priest
• Druid
• Paladin (Devo)
Group Buffs:
• Enhancement Shaman
Group Utility:
• Warlock (Gateway/Healthstones)
Debuffs:
• Assassination Rogue
• Demon Hunter
• Monk
So we’re looking at a minimum 50% of the raid team pre-chosen. Whilst it can be argued the enhancement shaman is a nice to have, the rest are pretty much required else you’re losing a lot of throughput.
All of these options do not have an alternative source.