Reddit and Lemmy supports upvotes and downvotes. This system is meant to allow good content to bubble up and bad content to sink. The goal is for people to self administer a filter bubble instead of relying on an opaque AI to sort content for the users, based on their inferred preferences.
Lemmy offers alternative sorting algorithms, some of which are not based on votes. This allows people to be able to dig up links, threads and comments that do not score well.
Downvotes are often used as a cheap way to signify a disagreement. They can be frustrating because the author of a post might feel bad without having a clear explanation about the disagreement. Downvotes can also be misused, e.g. for harassment campaigns and brigading.
Upvotes can also be assimilated to “likes”, which may signify agreement. Likes are well-known to be addictive, and some people become dependant of them, to the point of “living for social validation” at the cost of their own well-being. The “Infernet” series by the French media “Blast, le souffle de l’info” documents several cases.
Overall, votes (both up and down) can have a negative impact, at least on some users.
My understanding of your suggestion is that votes shall only be casted as part of a comment meeting a set of criteria for minimal quality. Automated screening are often gamified and are generally not well accepted by users. Also, I would argue that upvotes marking agreement will have a difficult time meeting the minimal quality criteria: agreement needs less words/clauses to be expressed than disagreement that would need to be supported by arguments.
Thus, I think that a system where votes can only be casted with comments would almost only have downvotes in practice. It feels like votes would therefore be redundant and that this system would be better off relying on another criterion than votes to sort content displayed by the forum/link aggregator. Someone suggested other engagement criteria.
Regarding the overall quality of posts in the system you present, I would agree that following the IndieWeb/POSSE philosophy could reduce the amount of low quality content since the author’s reputation would be directly impacted by the fact that their low quality content would be hosted on their own site. However, I would argue that user tracing and linkability would be increased, which can be an severe issue, especially for people expressing dissident opinions.
Regarding the use of a chat room for content creation, I suppose this is a mostly a question of habits and preferences. I do not like chat rooms because I find it difficult to track threads and comments and I prefer using a git send-email workflow with a good MUA, much like we do for code reviews at $WORK.