To be very pedantic, "Markdown standard" is basically a blog post written over 20 years ago and never updated.
Everything more "advanced" like tables, to-do lists and multi-line code blocks aren't a part of the "standard" as it was written, but were added on top by different implementations (like CommonMark) which are now commonly-mistaken for the original Markdown.
My point being that this isn't something unique to Obsidian, pretty much everyone does it slightly differently while still calling it "Markdown".
Everything more "advanced" like tables, to-do lists and multi-line code blocks aren't a part of the "standard" as it was written, but were added on top by different implementations (like CommonMark) which are now commonly-mistaken for the original Markdown.
My point being that this isn't something unique to Obsidian, pretty much everyone does it slightly differently while still calling it "Markdown".