What is the authenticity to this contention?
I'll direct you to The Struggle for Modern Tibet: The Autobiography of Tashi Tsering.

In other words, the Tibetans have not benefited!
That's pretty much what I said, no?

Not to belabor the point, but you seem to be confusing me with someone who advocates the PRC position on Tibet. My own moral position is that all parties concerned would be far better off if the PRC allowed both Xinjiang and Tibet to achieve independence and go their own way. However, this is not going to happen given the political situation as it exists today and for the foreseeable future.