@Illusory another insightful post, and as is often the case I agree with what you are saying! As another long-time user who primarily leverages comments in Fibery (we no longer use Slack, and in fact have basically eliminated internal Emails by setting up Fibery a certain way…), I think there are some even better ways comments can evolve to emulate Slack/Email/DM’s and give a team a full way to communicate around a company’s work and context better than anything out there…
So with Threads, I’m also not seeing a real movement forward here, similar to I think what you are saying. We already liberally use commenting in entities to communicate around them, so having the ability to essentially pin those comments to the left panel isn’t particularly useful. I’m basically reiterating what you are saying here:
I think this could be solved if Comments evolved into another type of item in Fibery, you could call them “conversations” let’s say. I talked about this here (including a quote from @mdubakov about Fibery replacing Slack):
I’d really like to see the ability for each comment to also live in Fibery on its own. Have a public ID, the works. We are constantly trying to respond to comments in one entity from comments in another entity - which is very useful because frequently you need to refer back to something in a related context. This feature could help with that, would be amazing if we could get it one day:
And this is all stuff I really ,100% back that would be a ton of help:
And you mentioned mobile as well…realizing the undertaking it is, for commenting and quick communication, it’s a must, so I’ll link to that yet again 
I’m excited for the direction all this is going and I know the Fibery team is in favor of much of this stuff!