I delved into this topic slightly in another thread:
Something to also consider, with forced personal loot it means that shared item slots have a higher frequency of being found and unique with a lower (even with armor stacking).
This expansion will be the first one where all slots are available.
In BfA you had a locked cloak + neck, so only rings were shared.
In Shadowlands there are no locked slots.
This mean that everyone can loot rings, clocks, necks and because everyone can get them they statistically have a higher chance of popping up. You can’t do anything with them as well as after a few weeks into a tier you really want a piece of loot from a boss and watch the raid loot 4 rings (for what could be multiple weeks in a row).
The amount of loot waste has increased this expansion, this in combination with the total amounts of loot being reduced from all sources is not a good recipe.
Master Looter didn’t have this particular issue, but it did have the issue of getting loot that nobody could use (example: looting bows but having no hunters).