Bookmarklet still works. There were few issues which makes the bookmaklet inferior to extensions so I stopped promoting it:
1. People do not understand where is “bookmark bar” and even what is it. The bar is not visible by default in modern browsers.
2. Firefox has blacklist of websites where all the bookmarklets do not work. The list includes “twitter.com” among others, to the bookmarklet did not allow to save tweets if you are using Firefox.
3. Since recently (somewhere between Chromium 80 and 85), `document.URL` on Wayback Machine pages returns url of the original page, having “http://web.archive.org/web/YYYYMMDDhhmmss/” prefix stripped. This breaks bookmarklet too.