Question about Black Temple next week for Glaives

How necessary is it to power up the Heart of Azeroth or get the legendary cloak etc. I’m seeing really conflicting posts. Some make it out to be like you’re nearly 2x as powerful.

I was excited to get the Warglaive transmog and even do the raid itself but after finding out I have to level up some outdated necklace just for this one thing it really soured me to the whole experience.

I’m tempted to just buy a run if I have to spend a few days powering up this dumb necklace. I don’t have world quests or anything in BFA unlocked so if I understand this list correctly I’ll have to do dungeons over and over? I really don’t know.