Is this common in whatever country you're in? If this happened where I went to school, there'd be words at the PTA meeting. Your principal is some kind of control freak.
Good question! I grew up in an upper middle class area of California: Thousand Oaks. I only went to school in public schools. From about 4th grade on there are great concern about students and conformity. Schools, principals, and even teachers were graded on how well students did in standardized testing, how well the students did in sports, and how many "state level" awards the students received. So, basically, if our goals were not in line with that, we were reprimanded by being told we would not "make it in this society". I remember very clearly being told by a teacher that I was destined to drive a street sweeper. This, of course, made me rebel more.
That being said, I can say many of the people in my peer group did conform to these standards and did become very successful. I can point at handfuls of my friends and acquaintances who went to school at MIT, Harvard, Stanford, and many other highly rated schools on full ride scholarships. A number of them have successful careers in medicine, law, politics and even professional sports. So, I guess the proof is in the pudding, it does work.
No one ever spoke up at a PTA meeting because parents wanted their kids to succeed, and the thought process goes that if they followed the program, they would succeed.
Of course, we won't talk about the suicide rate at my high school...
I agree with you. However, it may have been out of concern that they were being anti-social. There are better ways to address that concern than such a strongly and negatively worded reprimand. Subtlety may not have been that principal's strong suit.
It doesn't sound normal at all.