I’d really like to see this as well, but I think that it would depend on the tool that you’re using to create the site. If you’re using a static site generator on github pages, for example, it wouldn’t work as it would require some sort of script that would be incompatible with gh-pages. If you use wordpress and memberstack, you’d be able to use the wordpress api to send notifications to users.
I can see this being really useful for dashboards, but it’s not on the list of priorities for the devs at the moment.