It's interesting to look at the arguments being made here, and then doing a real world comparisons to other similar guilds. ThunderCats, Unite and Vanquish, and Control, all share similar levels of progression, and they also have similar iLvls when comparing gear across the raids.
I grabbed some stats from a few raid fights for each guild, which you can see below. The MC bosses are tank and spank. BWL has tank and spank and a threat drop fight
ThunderCats:
Baron Geddon - 84 seconds - iLvl 65 -
https://vanilla-twinhead.twinstar.cz/?boss-kill=416071
#1 DPS : 394
#1 Tank Dmg taken : 17,999
#1 Tank Dmg taken/second: 214
Golemagg - 113 seconds - iLvl 65 -
https://vanilla-twinhead.twinstar.cz/?boss-kill=416084
#1 DPS : 540
#1 Tank Dmg taken : 41,626
#1 Tank Dmg taken/second: 368
Ebonroc - 96 seconds - iLvl 65 -
https://vanilla-twinhead.twinstar.cz/?boss-kill=419211
#1 DPS : 560
#1 Tank Dmg taken : 33,412
#1 Tank Dmg taken/second: 348
Broodlord - 139 seconds - iLvl 65 -
https://vanilla-twinhead.twinstar.cz/?boss-kill=419190
#1 DPS : 435
#1 Tank Dmg taken : 41,259
#1 Tank Dmg taken/second: 296
===========================
Unite and Vanquish:
Baron Geddon - 73 seconds - iLvl 65 -
https://vanilla-twinhead.twinstar.cz/?boss-kill=417202
#1 DPS : 481
#1 Tank Dmg taken : 18,134
#1 Tank Dmg taken/second: 248
Golemagg - 98 seconds - iLvl 65 -
https://vanilla-twinhead.twinstar.cz/?boss-kill=417213
#1 DPS : 542
#1 Tank Dmg taken : 52,520
#1 Tank Dmg taken/second: 535
Ebonroc - 88 seconds - iLvl 67 -
https://vanilla-twinhead.twinstar.cz/?boss-kill=404046
#1 DPS : 821
#1 Tank Dmg taken : 34,942
#1 Tank Dmg taken/second: 397
Broodlord - 96 seconds - iLvl 66 -
https://vanilla-twinhead.twinstar.cz/?boss-kill=403996
#1 DPS : 614
#1 Tank Dmg taken : 28,424
#1 Tank Dmg taken/second: 296
===========================
Control:
Baron Geddon - 45 seconds - iLvl 65 -
https://vanilla-twinhead.twinstar.cz/?boss-kill=419069
#1 DPS : 940
#1 Tank Dmg taken : 19,646
#1 Tank Dmg taken/second: 436
Golemagg - 72 seconds - iLvl 65 -
https://vanilla-twinhead.twinstar.cz/?boss-kill=419084
#1 DPS : 665
#1 Tank Dmg taken : 27,419
#1 Tank Dmg taken/second: 380
Ebonroc - 119 seconds - iLvl 66 -
https://vanilla-twinhead.twinstar.cz/?boss-kill=419216
#1 DPS : 510
#1 Tank Dmg taken : 39,368
#1 Tank Dmg taken/second: 330
Broodlord - 165 seconds - iLvl 66 -
https://vanilla-twinhead.twinstar.cz/?boss-kill=419194
#1 DPS : 443
#1 Tank Dmg taken : 42,660
#1 Tank Dmg taken/second: 258
===========================
When you compare the 4 bosses, here's what you see.
Baron Geddon: ThunderCats had the slowest fight, lowest DPS, lowest tank damage taken/second
Golemagg: ThunderCats had the slowest fight, lowest DPS, lowest tank damage taken/second. UAV had extremely similar #1 DPS, but fight was 15 seconds shorter and average raid DPS was 10% higher. This is because they allowed their tank to take more damage.
Ebonroc: Control had the slowest fight, lowest DPS, lowest tank damage taken/second.
Broodlord: Control had the slowest fight. TC had the lowest #1 and average DPS. Control had the lowest tank damage taken/second.
Everyone knows by looking at stats from raid fights, the shorter the fight, the higher the DPS. But what maybe isn't quite as obvious, is that the tank needs to take higher damage per second, in order to allow the raid to do more damage per second. This is evidenced in these examples here. You can see this in higher end guilds as well. Just look at 2 bosses for Synced.
Broodlord - 60 seconds -
https://vanilla-twinhead.twinstar.cz/?boss-kill=415290#bosskills_players:0+5+4+1
#1 DPS : 1,101
#1 Tank Dmg taken : 24,965
#1 Taken Dmg taken/second : 416
Golemagg - 53 seconds -
https://vanilla-twinhead.twinstar.cz/?boss-kill=415583
#1 DPS : 1,083
#1 Tank Dmg taken : 27,074
#1 Taken Dmg taken/second : 510
The trend in every fight you look at is the raid DPS is higher when the tank (presumably) prioritizes threat over mitigation/avoidance.
Thank you for making this post to raise a discussion around itemization preferences in the tanking community.