“I’ve heard from a Shliach that he has to turn away majority of couples looking for him to be Mesader Kiddushin due to lack of proof of their Yiddishkait.”
This point should tell you so so much. Did you hear yourself say that? A MAJORITY of people that the kiruv workers deal with cannot even prove they are Jewish!
Do you realize how shocking this is?! A majority of these guys that are being “mekareved” may be outright goyim.
How can anyone wonder how the discussion in this thread is indeed a real issue and threat to Klal Yisroel?
You say that Chabad makes sure they don’t facilitate marriages with these questionable people; and that is to be congratulated. But, nevertheless, these potential non-Jews are hanging around in Orthodox Jewish circles (which is why they’re coming to a Chabad rabbi, in the first place, to try to get married), and even after the first rabbi says “no” they don’t give up. They try Rabbi B and Rabbi C until these goyim R”L marry a Yid under the pretense that they’re a Jew themselves. That is a frequent occurrence. And most of the time they may never be discovered. Then you’ll have their children thinking they’re Jewish and continue to intermarry with Jews.