只能用for的情况 :be beneficial for somebody to do sth。
其他的for/to sb/sth 可以任意用,不过to是标准搭配。
例句
1、I think it would be beneficial for each committee member to have a copy of the report.
2、 Lowering salt intake has a beneficial effect on blood pressure.
3、Relaxation classes can be beneficial to people of all ages.
4、Work experience is usually highly beneficial for students.