Per MDN it has been supported in Chrome and Safari for many years. While there is an alternative, I guess it should probably be in spec for web compatibility, although I haven't investigated its impact.

• https://www.w3.org/TR/2009/WD-cssom-view-20090804/#dom-documentview-caretrangefrompoint
• https://lists.w3.org/Archives/Public/public-css-bugzilla/2014Dec/0024.html