This is a "cliche" phrase in English these days, referring to another piece of 'evidence' supporting or decrying a viewpoint.

Below is a sentence and translation from the first URL reference:

「Innovations happen when people have the opportunity to add value; the number one proof point being the Internet.」(イノベーションというものは、人々が(イノベーションを生みたいと思う不特定多数の誰もが)付加価値をつけることができる可能性を持ったときにこそ起こるのだ。インターネットがその最大の証拠である。)

Also a search on Google for "proof point" (include the quotes when searching) turns up a bunch of other usage examples in English. I would choose to just translate as 証拠 (for noun) or 裏付ける (for verb) in Japanese for most of these usages.