It’s practically impossible to hit a duty time limitation so it has no effect on limiting the fatigue
I'm not sure how you come to that conclusion. The Variation flights regularly reach the limits. Some are planned to within 5 minutes of the extended (30 minute) limit despite the combined sector time being greater than 7 hours. Management are cute about this by saying the rule refers to a single sector, not to 2 X 4hour sectors together. The inevitable delay means discretion is required or the pilot goes home or to a different duty. Not many choose to press this point and the limit is exceeded. If this happens to your friend then he needs to stand up for himself.
Where are the doctors? Their integrity is compromised and they are relegated to attending to your minor complaints and dispensing a little SK or SKF here and there. They won't touch the larger issues.
Can anyone actually tell me what this magic FRMS actually achieves?
Yes. It provides an illusion of action by demonstrating intent by the company in the area of fatigue management. But you already know this.
It's time to leave, Pixy.
Full points, though, for the standard of your written English which is light years ahead of the usual in here.