Since this topic was linked to today, I figured I should update it with the conclusions I came to after putting some work into the idea.
I still think Discourse would make a good comment platform for the reasons I outlined in the OP.
In terms of how to do that, I think the work needs to be done on the Discourse end - ideally by improving the Discourse comment embed script. This could be done incrementally.
It’s technically possible to use Discourse as the server for a comment platform by doing all the work on a Discourse client (for example, the WP Discourse plugin), but due to having to manage the state between the client and Discourse, and get around rate limiting issues, it turns into a complex problem. It’s definitely more complex that something I want to be responsible for maintaining.
A few posts in this topic indicated that people would be interested in just allowing users to create Discourse comments on a blog site. From my point of view that’s not a great solution, but it can be achieved now with the Discourse API. Where things get complicated is in trying to create a full comment system, where users can interact with Discourse comments on a website in a similar way to how they’d expect to interact with comments on a typical mainstream news site.