I would imagine that in the times of the Gemara, a rebbi was different than today. Back then you had much smaller classes and they stuck with their teacher throughout the years. Yes, I am sure they came to love their students (although parents still generally love their children more than anyone!).
In today’s situation where teachers have new students every year and classes are 20+ students, I do not think they love their students as their parents do. Unless you have very low standards of love for your children.
And this thread makes me so sad that parents would allow their children to be struck by their teachers.