Hi @songhn233 and thanks for this PR. I see it's your first to the project—welcome!

Typically, we try to avoid documenting very new or unstable web features, particular features that exist only as proposals with little or no consensus. You've discovered an interesting case where we've continued to cover a feature that's no longer useful to web developers (in a poorly-linked part of MDN, luckily).

I'd welcome coverage of these alternatives, when they've progressed to the prototyping stage in working browsers. Until then, I think we should avoid bringing them up, until they're of practical use to web developers generally.

I'll open a new PR that deals with this content in another way. Thank you for bringing this to our attention.