This is NOT a requirement despite the common belief, I know plenty of "teachers" across China who got their Z-visas and RP without having ever been to college themselves. And some got their visa way after the last update of the rules.

Outside of teaching, it is not a requirement, many German engineers just do apprenticeships at high school, yet end up getting sent to China for certain projects. However, they do tend to have a good deal of technical work experience and knowledge that most 'deechers' don't have.