This has been brought up for quite a while. I'm East Asian and come from a family that never runs short of tea. My father in particular, who actually studied tea in college (some agriculture major) and drinks tea on a daily basis for all his life, is the baldest among his brothers.
On the other hand, tea is commonly used to combat mild hairloss and SD here. Topically though. Some people soak their heads in brew of tea, tea seeds, etc. It's all over the Chinese SD boards. Some SD patients swear by it. For hair loss my impression is those who benefited from it are mostly female.
But seriously judging from these studies, EGCG, equol, quercetin, tumeric, and a wide range of naturals can basically cure hair loss already. But the fact is it just doesn't work that way...