Certain systems of yoga have strict guidelines about how yoga should be practiced. But when you are too rigid about sticking to your particular system, the human element gets lost.
This "my view is better than your view" attitude reflects more poorly on you than the ones you are bashing.
Yoga is not a one-size-fits-all package. Can you accept other teachers and traditions and the fact that some forms of yoga are not for everyone?
We're all making our own ways through this treacherous terrain called life. We're doing the best that we can. If you have found a spiritual path that helps you, that's wonderful. Respect others' paths as being valid for them.
Teaching yoga is an advanced practice. Be grateful for the opportunity to teach and to learn from the experience. Because the things your students won't tell you directly are probably the things you most need to hear.