Browsers have had widespread support for processing files via drag-and-drop and the <input> element since HTML5 (< 2015). The last holdout on allowing the filepicker to accept a full directory (and its subdirectories, recursively—rather than 1 or N individual files) was Safari sometime around (before) 2020.

The Chrome team's new, experimental APIs are a separate matter. They provide additional capabilities, but many programs can get along just fine without since they don't don't strictly need them in order to work—if they would ever even have end up using them at all. A bunch of the applications in the original post fall into this category. You don't need new or novel APIs to be able to hash a file, for example. It's a developer education problem (see also: hubris).