They know it's not a crime, they just want morons like you to THINK it's a crime. And guess what? It worked. LOLThe simple answer to the question posed in the thread's title is that "immunity" allows a witness to testify (in some cases waving one's 5th amendment rights) without fear of inculpating oneself....
Prior to such immunity being given, a witness meets with prosecutors in what lawyers call a "proffer session" where the information is gauged for both relevancy and accuracy.
The two guys mentioned in the thread's title have much to offer prosecutors regarding Cohen AND Trump. Sleepless nights for Cohen...for sure.....but even more nightmares for Trump AND his family.
Because like Cohen, they were offered lesser charges because Mueller thinks he has something incriminating against Trump. Cohen actually pleaded guilty to something that even isn't a crime, in order to get the more serious charges dropped.
If it wasn’t a crime, the judge would not have accepted the plea.
But keep drinking that Trump Kool-Aid idiot.