Then why did they deliberately make it compatible with Open Feature, explicitly making it easy to swap out a different Open Feature provider?

Oh, that's right, you just spouted a "big company bad" mantra without bothering to read the article. Look, I know saying RTFA goes against the HN guidelines, but the amount of increasingly lazy spew i see from folks (or bots) who haven't bothered to read the article is so tiresome and annoying.