You do realize the link you are trying to use for citation is updated material for current retail mechanics, yes? I guess not. The mechanic you're referring to in this thread is a raid lockout system that was implemented in patch
4.0.1, aka Cataclysm pre-patch, which applied the new per-boss lockout system.
The paragraph(s) you are trying to use as citation is updated material that is intended to explain the difference between normal VS. heroic raid locks - and normal/heroic VS. mythic raid locks. Which means that currently, normal difficulty WotLK raids use the flexible raid lock system, whereas heroic difficulty uses a hard ID like in previous patches.
The reason this is stated to start in Wrath in the link you're citing is because prior to WotLK, THERE ARE NO HEROIC RAID SETTINGS.
You're citing directly to the section in this link called "Flexible Boss-based Lockout".
Then look here, under Dungeons&Raids, where it explains the implementation of "Flexible Raid Lock System".
http://www.wowhead.com/patchnotes=4.0.1
So before you decide to go and get snide with people replying to your thread, I suggest you do a little more thorough research before jumping to conclusions based on bits of information you've found and misunderstood.