That’s why I wrote some randoms in big groups (I should have written guild groups) because there was a certain threshold, when you could activate it despite having randoms with you if I am not ill informed (I started raiding again only when uldir went live, I paused since firelands before).
I’m sorry, I like a differentiated view before I make up my mind.
You got me. 
For farm runs, this will be the case very quickly.
I didn’t have the option to watch the video, but reading the title and the first comments, this has to be the conclusion, that this was meant to be the “abused” mechanic.
If this is not the case enlighten me, but
makes me think I am right. (I will watch the video when I have more than a few minutes of time)
Overall, I am no big fan of PL, but I don’t mind it either.
For discipline priest as well as shadow priest, intellect is the best stat and therefore I rarely get higher item level gear I am not willing to wear. We have a big portion of raiders outside of our guild, but within our raid community, so we would have PL either way. And I agree with the previous state, that groups with a big portion of non guildies should keep PL, because fair ML works in guild groups but I kind of doubt it works well in groups with a big fluctuating part.