RSS may not have been "designed to work with comments in mind", but Atom supports them: https://www.xml.com/pub/a/2004/06/16/dive.html

Bristly pop cultural misuse of the term "algorithm" notwithstanding, a better solution that I haven't come across anyone else mention: make them explicit, not hidden.

When it look like Dat might've had enough steam to take off (ca. 2017–2018), I wrote a draft straw proposal for how to solve the "discovery problem" with e.g. Fritter—i.e. the problem that because you only "receive" replies and other messages by checking the feeds of the people you're following, you'll be unable to reply engage with strangers who appear (or have a stranger engage with you in their thread) unless something happens like a mutual acquaintance alerting you out of band ("hey, did you see @foo's reply dat://foo.example.net/posts/ukifxdgbh.json?").

The idea is that there is a special kind of feed operated by some service provider that specializes in doing exactly that. If you find Facebook valuable, for example, then you are free to opt in and subscribe to the Facebook analog that pays attention to all feeds and works to surface interesting content for you. Under this model, unlike the Facebook regime, "leaving" is as simple as unsubscribing to that feed (and going with a different provider if you want).

This differs from LDN, where the the annotation service is squarely under the control of the document author. This is also using sensor attachment in a different sense that the way it first appears above. The application is more akin to RSS. With RSS, the links exist in some other "document" (or something like it; generall can be modeled as OPML, even if it's really, say, an sqlite store).