Conversations should definitely be encouraged equally even if they're not "hot" and seeing new posts at an hourly frequency. Some people have high signal precisely because they're doing things other than authoring high-quality prose for a bulletin board, and if their participation is only incentivised when they spend hours catering to artificial engagement metrics, then they might avoid the place entirely and stick to doing their thing and posting about it through services that deliver content sequentiallly rather than algorithmically.