@vinod367 Yes, they are. The main difficulty with body weight calisthenics is incremental progress. How do you know you're progressing week to week once you can already do 20 pull-ups in a set?
Weighted pull-ups give you that metric. You can add a 2.5 or 5 plate to the stack and apply double progression to the exercise.
It's much harder to do sternum pull-ups and so we often take the easier version of chin to bar as the basic standard.
The weighted pull-up also gives you a weighted stretch at the bottom, akin to a weighted dead hang, something that can't be easily replicated with bodyweight pull-ups. You could say that people often cheat themselves out of that stretch and the bottom but I think the folks who do that would also do that on bodyweight variations.
That being said, the weighted pull-up is not a magic exercise. It's just one variation and I have others like L sit pull-ups and wide grip pull-ups in my program. But it's a good tool to have and I wouldn't dismiss it because some of the benefits it offers are unique to it and can't be offered by other exercises in your program.