I would say No. Being a teacher doesn't make you better - learning makes you better. If you have to learn to be a teacher, then you'll become better. Teaching only helps you retain what you know, but in the world of IT everything changes daily. Because of this, you cannot just rely on teaching, you have to get your ... bum... off the couch and learn.
I have met may IT professors who were ignorant when it came to their actual field.They had certificates, courses, papers on the wall, lots of "show". Sure they could talk the talk, but if you EVER got off of the prescribed course schedule they would flutter, stutter and fail. They couldn't handle the pressure of things changing. They didn't change with the times, they taught what they knew, which was obsolete.
So let's turn this around again, I've had a few professors that were amazing. They were developers, senior developers, lead developers, directors of application development, then they became programmers. They knew real world scenarios, they knew that 99% of the stuff in text books didn't prepare people for real life work, so they changed it up, kept it current.
12 years ago my grade 11/12 IT teacher gave me an offer. If throughout each school year I was able to break his security / firewalls etc. at school, he'd give me an A+ (100%) in the course, regardless of my work. Heck, I helped him plan the course as I working as a jr. developer back then. That offer he gave me made him (at the time) an expert at windows NT security. I did get 100%, I had to steal his UN/PW and then lock him out... it was the only way in the end... But needless to say he got better as a teacher and in IT because of teaching - he worked WITH his class - not on his own agenda.
So where do you draw the line? Draw it on the attitude of the teacher. If that teacher is willing to learn, they will get better. If that teacher is just riding the wave, getting paid, and could care less - they're going to get worse.