Hasta La Motion!

Okay.. Hello to all… I have a rotoscope question when it comes to working in the industry… Apparently i heard from a few sources that as a Roto Artist.. you are supposed to Rotoscope anything( character or any other object) and then give the matte to the compositor… Now the thing that i heard is that you are not allowed to give the feather or the matte blur settings as people said that the compositor would fix it by himself.. Is that true???
If so.. what about shots that have so much motion blur… It is possible to rotoscope to a certain extent and then experiment with the feather..If you are not allowed to touch the feather settings it would be hard to deal with motion blur shots wouldnt it.. How exactly does this process work??