Agree, but certainly it is not the most desired thing during 1st year in graduate school when u have to take a lot of exams and start ur research work. Why most distiguished programs clearly state that u do not need to TA while u r a freshman
? Because tops have bags of money, and thus do not need to force int.students into TA when they struggle with English, at least initially.
Naturally, later on in one`s career in graduate school a semester of TA can do more good than harm, boosting confidence levels, language communication and presentation skills.
Besides, these qualities are not easily measurable & one could have acquired them prior to entering graduate school.