you are forgetting the fact that the juubi is humongous. it's gonna take a lot to actually hurt it. obito on the other hand is much smaller, human sized. that means it's gonna take much less to blow him away.
FRS wasn't enhanced by senjutsu like how the rasengan was.
Naruto's FRS didn't nothing to Juubi.
But Naruto's regular Rasengan made Juubito fly.
How?
Juubito>>>Juubi in every way.
So how did a Juubi tank FRS?
Wait, does that mean SM Naruto can solo Juubi with 1 rasengan?
Damn man do you ever read the manga??
It doesn't show the juubi tanking it but still. FRS was able to cut through the Juubi's tails.Actually it was. Check chap 612 or look at the scan I posted somewhere in this thread
Sorry but the FRS has senjutsu too.
No the FRS he used along with sasuke did not have Senjutsu on it!