For there not being healers required, there sure is a lot of healing in that video.

Jokes aside, this isn't uncommon in any game. People do weird things for a challenge and for fun. All Paladin runs, all Gunbreaker and Warrior runs, etc. Just shows if you can follow the mechanics perfectly, which sadly 99.99999175 of players cannot, you take less damage. What this is showing is perhaps certain tanks have too much healing.