One of the reasons we use seniority when bidding for working positions is because of time constraints, as you know the CSD has 13 mins to brief crew and be through the security check point 2 mins later.
To have a full discussion to find out the depth of 13 other cabin crew's experience and still include the mandatory elements of the briefing with in 13 mins isn't practical.
As I'm sure you know CSD's are managed on punctuality muddling through the service is far less important to the powers that be.
As in any task the "want to do the task" is far more important than "the skill."
It's a fine balance for CSD's to find a happy medium getting the "want" and the "skill" right to benefit all