It won't kill your students either. If all you are doing as a teacher is telling your students how great they are then you are doing them a disservice.
Tell them when they are wrong. Tell them when they are acting inappropriately. Tell them when their effort isn't good enough. A little dose of reality is good for your students.
Somewhere along the way giving compliments seems to have become the only way to go. Sugar sugar sugar. This kind of approach is going to make your students delusional.
The same thing is also true in the other direction. You don't want to only criticize, of course. Praise when you can, but criticize when it's deserved too. You will be much more believable. You will be helping your students as well.