This works for viewing all the comments so far, but it doesn’t solve the discussion aspect since commentors from each community won’t be seeing or responding to the other comments. This is a bigger issue with smaller communities, where they’d mostly be top level comments / chains with minimal depth from each smaller community. Yes you can see all the comments, but the discussion quality is poor.

It’s also not as helpful when the automation fails. Something I’ve found is that the ‘crosspost’ field starts to get crowded on posts that link to a popular website. Combining comment sections from ALL of those posts isn’t as useful as having some intentional action from the OP.

A key aspect about this proposal is that it requires the OP to do something. If it doesn’t make sense for a community (ex. different intents behind the Politics communities), then OP shouldn’t lock their post. If OP does it anyway, then you can downvote that post.