"limitations" to the student-centered teaching of mathematics?

Constraints are issues that can be overcome. Limitations make one think of reasons why something cannot be achieved. Some "limitations" of student-centered learning:1) fear of loss of control by teachers; 2) lack of classroom culture necessaryfor student-centered learning to occur; 3) lack of knowledge on teacher's part on how to manage/facilitate/monitor activities in such a classroom.

My current thinking is that studen-centered teaching is a good idea - students construct their own ideas and learning takes place - is is the number 1 goal. When students are learning, discipline problems decrease and classes can be fun.