According to this dude from the thread at the time: Is Keystone Master really supposed to be that easy? - #15 by Rallos-ravencrest
KSM was only achieved by less than 25% of accounts that had engaged with M+ content.
This means I was better than 75% of the PvE playerbase, and again, I did it:
- with PvP gear only
- 0 optimization
- no tier set
- no consumables
- I didn’t read any boss strat or mechanics
- I didn’t know what the affixes did or what they were
I went in completely blind and I still got it in a single week because PvE is just that easy.