Embedded help is only not popular when it gets in the way of the user trying to do their work. No one is going to complain about embedded help on their page when it's actually truly helpful to them And it doesn't prevent them from doing their job.
I interact with online embedded help all the time on web sites I visit. Most of them are done in a very nice and classy way (but some of them are not…). Inline help icons, text, buttons or even dialog boxes that pop up once in a while with critical information that I would not have known about otherwise. If done in a tasteful way, it all helps ends up helping the end user in my opinion.
Active help versus passive help both have their place. Active help can get annoying if it's not helping anymore and just being intrusive and getting in the way. However, there are definitely ways of embedding active help in an application that truly helps the user. Example that comes to mind is how a tooltip that appears in Upwork when I put my email address in a conversation.
The tooltip is letting me know that protections provided by upwork differ if I take my conversations outside of the platform. That's useful to know for an employer like myself just in case if there is any conflicts that later arise with the contractor.
At the end of the day, the simple rule is that embedded help has to be helpful for it to be perceived as useful and not intrusive by the end user.