Correct!
Why? Its simply because of the shared 10/25 ID system. People mainly raiding 10mans used to be able to PUG 25mans when they had time and the other way round. Why was that so important?
1. Many people who dont have time to play twinks used to be able to enjoy the raid for an additional evening with their mains chars
2. You used to be able to just PUG this 2nd raid evening when u had time, no need for sceduling there. Even possible if you cant make it to all of your guilds main-raids. The new system with boss-wise IDing isnt as good as blizz thinks when it comes to this. You killed for example Shannox in your main raid, no PUG group is ever gonna take you...
So blizz tried to limit the time people could spend with one char in a raid in order to keep content more interesting for people for a longer time... but the failed so very hard in not seeing this would mostly just be bad for those players that can maybe raid only 1 day in their main-raids and took them away a possible second raid day... hope they gonna back off the ID seperation... even if they keep loot the same