One problem is that the API call that returns the feed doesn't provide crosspost information (unless that's changed in 0.19.4+ since i'm still developing against 0.19.3).

Crossposts in the feed have to be done client side, and you can only "roll up" ones that have the same URL (Tesseract can optionally roll up on identical titles if there's no URL). However, that's limited to just the ones that come through in the same fetch (unless you store all posts locally, which is something I'm considering in the future for offline support; most apps don't).

The API call that populates the /post page does provide that crosspost data, and I've thought about making an option to combine the comments from each into one "megapost". But there are a few problems with that:

1. Officially, crossposts are only compared against the URL. The crossposts may have different titles, and one or both may have different text in the post bodies. Which do you display?

2. Culture clashes. Let's say there's an article posted called "Ford Releases Their New Monstrosity 5000". It gets posted to c/cars and c/fuckcars by different people with different intentions.

The tone of the comments would be wildly different since the two communities are basically ideologically opposites. The replies to comments that came in from c/fuckcars would be responding to car enthusiasts from c/cars and vice-versa. It would basically be a form of soft brigading.

3. It would be confusing for moderators to have multiple communities' comments in the same post. What flies in one may violate a rule in another. Mods would only be able to take action against those in their community and not all.

I've wanted to do a feature like that for a while now, but every time I've tried to plan it out, it always seems like it would just make things worse. Even with indicators as to which community the comment came from, it's still not ideal.