I have a question because there are opposed opinions about it and I think there are a few of you here that may have the definite answer (if possible with sources).
Let’s take a simple example. A raid of 20 players. 5 of them already killed the boss before. The raid kills the boss.
The 2 options are :
1 - A number of items depending on the raid size (counting the whole 20 raid members) is randomly given to players members with a chance that a player that have already killed the boss is chosen. If that happens the item given to an non-eligible player disappears. If worst luck happens and all non-eligible player are picked, it would be possible that there are 0 loot for the raid in theory (if the number of items for 20 players is 5 or less).
2 - A number of items depending on the number of eligible players in the raid (15 in this case) is randomly given to the 15 eligible players in the raid, totally ignoring the 5 other players. This means the number of non-eligible players in the raid means nothing to the loot.
The random distribution takes other things in consideration for each player but that’s another topic.
If you have certain information on this matter I hope you’ll share it because I didn’t find my answer yet.
Thank you for your attention.
PS : Ah the forum thing selected my WoW Classic character but I’m obviously asking this for BfA loot system.
I cannot be a 100% on this, but to my understanding, this is how it works: If you have 20 players in the raid, the game will decide how many items it will give out to the raid based on the amount of players. I believe this to be the case due to the very consistent amount of loot drops, if this was not the case then I would’ve seen a boss where nobody gets any loot at all at least once, or everyone gets something.
Now is the tricky part, what happens if there are people who have killed that particular boss already in your raid? Well, I believe the game simply subtracts those players from the calculation when deciding how many items it will hand out. So for example, you have 20 players but 5 are locked, well now the game will distribute the loot as if there were only 15 players in the raid.
Does this affect others? Yes and no. Having people with lockout in your raid wont affect your drops even though it may seem like it does (less loot drops than usual), but at the same time, those players who are locked cannot get loot that they could for example trade to others. It’s a minor thing, but it still does affect others in the raid slightly.
Please know that I don’t know how the loot system actually works. This is based on my many years of raiding and experiences. I could have something wrong here, or I could be right. I don’t know. But it’s the best I came up with.