Am surprised I've not gotten a more violent reaction to what I propose in the OP from people here? Not that I said it to be annoying, I really think it might be true.
Dogs like ovcharkas, kangals and etc etc etc, all the cool LGDs basically, are simply dogs like the above, crossed with mastiffs and bullbreeds, and to the detriment of their performance in LGD work, but maybe to the benefit of their aptitude in dodgey backyard fights and their suitability as pets/personal guardians.
I think this is why LGds are like mastiffs, not because they're really related at the core but because, most of the cool hyped up ones are LGD/mastiff hybrids. The ones that just guard sheep and don't get sh!t spun about them, just are built for their role, are not mastiff like at all.
This is surely not a popular opinion, but would love to hear from people why they think I'm wrong.
Hm, let me start with that I don't even know if I agree or disagree with your premise. Are Shars LGDs on steroids because of mastiff blood? Most certainly not, they've been like that for a long time. I would say that "LGD" breeds as you have in mind are just watered down variants of these eastern LGDs. In short, this kick ass ingredient in eastern LGDs developed more or less on its own, due to a harsh selective regime.
Now, do people cross mastiffs into Shars or COs or Kangals to develop the ultimate fighter? Yes, probably. Those hybrids, as you say, are then used for "jobs" other than livestock guarding. I just don't know if that's really necessary to hype up the breed. I also don't know if weak examples of LGDs are an indicator that the tough examples must be crosses. That would be like stating that the APBT must be crossed because the show AmStaff is worthless. It's just different selective criteria in most cases. No?