Likely because the element authors didn't want to overload the existing input semantics. You are talking about <calendar /> not <input type="date" />. Its the s

Likely because the element authors didn't want to overload the existing input semantics. You are talking about <calendar /> not <input type="date" />. Its the same semantic issue that lead to <button /> and <input type="button" />, with different functionality/support in different browser(s), and why we have auto-fill libraries that eventually became javascript component libraries, got rolled into development frameworks and turned into hyper-adware... Its "hilarious" but an "input" that does nothing but show an input calendar is arguably better. Otherwise, you're not writing (semantic) html, you're writing <insert ui framework>.